Mazda Rotary Club

I\'m new here but not to rotary engines as I have owned an RX8 for nearly 12 months now.

I must also confess to having an interest in oil debates as it is my livelyhood and I advise many Car Clubs on the correct and best oils for their Members Cars.

I have been reading the "oil debates" here with some interest and though that it would be worth sharing what I know and my opinions with you all.

The subject of synthetic oils in the rotary engine is a much debated topic on car forums and clubs around the world but when looking at the tecnical aspects of the argument, no one has ever convinced me (or at least not until now?) that they actually cause harm to the engine or shorten its life.

To start with some basics, we need to remind ourselves what an engine oil is designed to do. It must:

Lubricate

Oil must lubricate engine components so that they will easily pass by one another without a significant loss of power due to friction. At start-up, this is especially true. Once running, engine oil must create a film between moving parts to make them "slippery" which increases power, performance and efficiency.

Protect

Oil must keep engine components from coming in contact with each other and provides vital protection against wear. Engine oils also protect against corrosion of engine components.

Clean

If an engine doesn’t remain clean, it will not remain efficient. Deposits within an engine reduce fuel efficiency and rob your engine of performance.

Cool

Engine oil is responsible for a large percentage of the cooling that takes place within your engine. The radiator is only responsible for cooling the upper portion of your engine. The rest of the critical engine components are cooled mainly by the motor oil within your engine.

Contrary to popular belief and a healthy pinch of myth, all oils are not petroleum based or derived. Oil technology has moved on like everything in life as the chemists strive to create the perfect lubricants.

There are two main components that all engine oils are made of and they are basestocks and additives. The basestocks normally make up between 70 and 95%. Additive chemicals are then added to enhance the positive qualities of the basestocks and to overcome any negative qualities present.

There are two main types of basestocks used, petroleum and synthetic. Petroleum basestocks are a purified form of crude oil and have been used as automotive lubricants since motor oils were first developed. Synthetic basestocks, on the other hand, are chemically engineered in a laboratory specifically for the purpose of lubrication. They are engineered from pure compounds that contain no contaminants which must be removed via purification. Synthetic basestocks have been around for many years but have only been used in the automotive market for the last 30 years.

The main types of oil basestocks commercially available in the market today apart from the traditional mineral oils are as follows:

Hydrocracked (also referred to as Molecularly Converted Mineral Oils)

These are so pure and refined, they can now be called synthetics. They are not made from true synthetic basestocks (as previously mentioned) but have so little in common with traditional petroleum basestocks, that it doesn’t make sense classify them as petroleum oils. Petroleum basestocks can be put through a super-extreme refining process called “hydrocracking”. It is completely legal for lubricants manufacturers to label these oils as "synthetic". These are extremely high performance petroleum basestocks, will not perform to the same level as true synthetic basestocks like PAO (poly alfa olefins) or Esters.

Hydrocracking results in a basestock which has far better thermal and oxidative stability as well as a better ability to maintain proper viscosity through a wide temperature range - when compared to Mineral oils.

The most common types of Synthetic basestocks.

Poly alpha olefins (PAO\'s)

These are the most common synthetic basestocks. Many synthetics on the market use PAO basestocks exclusively. Also known as synthesized hydrocarbons, they contain absolutely no wax, metals, sulfur or phosphorous. They have extremely low pour points and are very thermally stable. One drawback to using PAO\'s is that they are not as oxidatively stable as other synthetics unless properly additised.

Diesters

These synthetic basestocks offer many of the same benefits of PAO\'s but are more varied in structure. Their performance characteristics vary more than PAO\'s. When chosen carefully, diesters provide better pour points and thermal stability than PAO\'s  and are a little more oxidatively stable. Diesters also have very good inherent solvency characteristics which means that not only do they burn cleanly, they also clean out deposits left behind by other lubricants, without the aid of detergency additives.
They are also surface-active (electrostatically attracted to metal surfaces),

Polyolesters

These synthetic basestocks are similar to diesters, but slightly more complex. They have a  greater range of pour points than diesters, but some polyolester basestocks will outperform diesters. They are also surface-active.

Premium quality synthetics are normally a blend of more than one type of PAO and/or PAO basestocks with diester and/or polyolester in order to create a basestock which combines all of the benefits of these basestocks.

The Synthetic Myth.

There are many oils on the shelves today labeled as “synthetic” but in the true sense of the word they are not. They are the “hydrocracked” petroleum oils previously mentioned and although generally superior to mineral oils they are not of the same quality as true “made in the laboratory” synthetics.

So, why are these highly refined mineral oils called “synthetic”? It was all decided in a legal battle that took place in the USA about ten years ago. Sound reasons (including evidence from a Nobel Prize winning chemist) were disregarded and the final ruling was that certain mineral bases that had undergone extra chemical treatments could be called “synthetic”.

Needless to say, the marketing executives could not believe their luck! They realised that this meant, and still does, that the critical buzz-word “synthetic” could be printed on a can of cheap oil provided that the contents included a few percent of “hydrocracked” mineral oil, at a cost of quite literally a few pence.

Synthetics and the rotary engine.

How many times have we heard it “do not use synthetic oil in the rotary engine?”

Too many and there will be many more but, it’s a pretty meaningless statement unless we as rotory engined car owners and the person making the statement fully understand the meaning of the word “synthetic”.

As I have stated before, most oils on the shelves today do not contain true synthetics, they are merely highly refined mineral oils and as such are just a high performance mineral oil.

I have done much research into this topic since I picked up my shiny Velocity Red RX8 nearly 12 months ago and I have to say with no definitive conclusion. I know of RX7 and RX8 Owners that use fully synthetic oils in their rotories with no evidence of any ill effects to the engine, it’s not surprising as they are without doubt superior lubricants.

However, when I questioned Mazda UK about the use of Fully Synthetic oils we received the following reply.

“The Mazda RX-7 engine contained rubber parts that would be affected by synthetic oil so dealers were told not to use it in rotary engines. We asked on Mazda RX-8 training if this was still the case for the new Renesis engine and were told that although the rubber parts in the engine were all now believed to be synthetic oil compatible Mazda Corporation had not done any testing or evaluation with synthetic oil.

Mazda Corporation has developed and tested this engine using mineral oil and has recommended its continued use in service, I would consider that straying from a proven and tested specification is not some thing that we could endorse. Although the oil may be a superior lubricant, there is no requirement for it in an engine with only three major moving parts none of which are reciprocating and all of which are in near perfect balance.”

In itself this answer is not really conclusive, the seal compatability problem seems to have been solved but it’s not been tested. So I decided to take a trip all the way to Stoke (Belper to be precise) to talk with the Silkolene technical boffins and the chief chemist about Mazda\'s reply and synthetic compatability.

Their first comment on Mazda\'s statement was that depending on what synthetic they are referring to i.e. PAO (Poly Alpha Olefin), Polyolester or Diesester the seals would be affected in different ways.

PAO\'s always shrink seals
Esters always swell seals

They (Silkolene) tested a mixture of PAO/Ester in the early Norton Rotary Bikes as they were asked to formulate a "proper" synthetic for Norton and they found that the correct mix (not 50/50 I might add) had the affect of no swell or shrinkage of seals. Oils have come a long way since.

They told me that "proper" synthetics PAO/Ester blend types are of great benefit to the Rotary engine and the "shear stability" of these oils added to the "polar" benefits of ester make these oils perfect for the engine or at least this was their opinion.

Their reply to Mazdas comments on the engine itself were as follows:

This does not make sense, Esters have been used in the aviation industry for more then 50 years..................Think about it!!

Anyway, my conclusion is that "true" synthetics are better and that\'s a fact but they cost more and are not so readily available so in a car that uses around 1 litre per thousand miles was this a commercial decision as the oil\'s not in the engine long enough to "shear" or "degrade" to any great extent?

So the next question is what do I use?

I follow the handbook and use a "hydrocracked" (petroleum based highly refined mineral oil) which is in my opinion and from a chemists point of view labelled as a "synthetic" but it\'s not as the basestock is petroluem. It is a 5w-30, a 10w-30 can also be used for different ambient temperatures.

As for the RX7\'s well it\'s personal choice really and as I\'ve said before, synthetics are better but most are not true synthetics so as long as you stay clear of 100% Poly Alpha Olefin based oils (Like Mobil 1 as an example) which would give the highest levels of seal shrinkage you will be fine. An oil with a good percentage of ester basestocks will counteract this shrinkage.

There is no doubt that "hydrocracked" oils that are either Fully or semi-synthetic are fine to use because they are merely highly refined mineral oils will give you better protection than a plain old mineral oil. Silkolene actually recommend the use of their 10w-40 semi synthetic products in the RX7.

So, there it is, complicated until you know what "synthetic" really means. Hopefully this sheds some light and some food for thought on this slippery topic.

If anyone has any questions, please feel free to ask.

Cheers
Simon

An intersting read, thanks for that :)

I think a lot of people use Castrol GTX 10W-40(http://www.castrol.com/castrol/productdetailmin.do?categoryId=82915280&contentId=6008816), a highly refined mineral oil that is readily available and proven, but when it comes round to buying my next tub, perhaps I\'ll evaluate what is available in the semi/synthetic range.

excellent write-up

Guess what I bought for the rex before it arrived........Mobil 1 motorsport....Arghhhhh

My car looks like its had Motul used on it in the past going off the stickers and service sticker inside the door.

Looked it up and they do a nice Mineral oil that looks just the ticket :D

Good job I didn\'t touch it, oil is still clean and the filter looks new so I\'m guessing it was done in japan before it left?

In my opinion and I actually sell 6 brands of oil, it\'s hard to beat Motul and Silkolene for quality.

This is only my opinion and I do respect the views of others unless of course they use shop brands;)

Cheers
Simon

Hi Oilman, no disrespect, but I wondered how long it would take for you to get on here, I noticed you\'re on every forum possible;)

Im sure you experience will be welcome.

Can I also point you in the direction of our terms and conditions for trade people.

http://www.mazdarotaryclub.com/legal/mazdarotaryclub_terms-and-conditions.htm

Great write-up Simon, very interesting info.

Does thi sbasically mean that stuff labelled \'semi-synthetic\' is hydrocracked or could \'fully synth\' include that too?

I use 76-racing mineral mainly because that\'s what was reccomended by the people who built my engine, not too much more pricey that castrol but much harder to get hold of!

Iain

QuoteOriginally posted by g11ary

Can I also point you in the direction of our terms and conditions for trade people.

Thankyou and no problems. I\'m not trying to sell anything but If there is demand then of course I will become a trader willingly with the Clubs permission.

Regarding other forums.

Many Clubs (around 100) subscribe to our "Clubs Oil Scheme" and as part of it we offer an "online" advice service. You will have noticed that we usually have a dedicated thread with the Club Committee or Sight Owners permission.

I\'m not hiding the fact that we sell oils but it\'s always above board.

Cheers
Simon

QuoteOriginally posted by iaint

Does thi sbasically mean that stuff labelled \'semi-synthetic\' is hydrocracked or could \'fully synth\' include that too?
Iain

Yes basically but it\'s a little more complicated than that.

Most oils labelled "synthetic", "semi-synthetic", "part-synthetic", "synthetic blend" etc are only "cracked" petroleum oils with some exceptions.

0w oils normally contain "PAO\'s" because petroleum oils simply cannot meet the -35 degC pour point required to pass API\'s or ACEA\'s tests.

5w oils can just about be made with petroleum oils although it is common to put a small amount of synthetic in to pass the -30 degC pour test.

So basically some 5w\'s, and just about all 10w, 15w and 20w oils are petroleum based.

The noteable exceptions to name a few are Redline, Silkolene, Royal Purple, Motul, Amsoil and Fuchs although these companies all produce a different range of hydrocracked and mineral oils which are normally half the price of the true synthetics.

This is a general rule, price is a good indicator though.

Cheers
Simon

So when yourefered to Mobil before did you mean the 0W40 they do? I have always used the 10W50 motorsport stuff they do so would this be good/bad in a rotary???

Also, whats the best Motul stuff to use, if this is currently in my car I will probs carry on using it

Thanks

Thanks for the info, Simon. You covered the point on seal damage from using PAO`s and esters, but what would the effect be when using these base oils with the oil injection system? Is there any indication that the petroleum based oils burn cleaner than the Synthetics?
I use 2 stroke oil as premix and have recently started using 10w60 "fully synthetic" oil produced in Germany. Would this be a true synthetic, and what sort of base would it be?
Many thanks,

John
88 GT-R

QuoteOriginally posted by wiggy
So when yourefered to Mobil before did you mean the 0W40 they do? I have always used the 10W50 motorsport stuff they do so would this be good/bad in a rotary???

Also, whats the best Motul stuff to use, if this is currently in my car I will probs carry on using it

Thanks

I think you\'ll find it\'s 15w-50 and if it\'s Mobil 1 then it\'s poly alpha olefin basestocks so in theory shrinks seals. However as I stated above, I know of many people using proper synthetics with no problems.

The Motul range is as follows:

300V (Double Ester/PAO Fully)
8100 (PAO Fully)
6100 (PAO Semi)
4100 (Hydrocracked)
4000 (Mineral)
2000 (Mineral)

Cheers
Simon

QuoteOriginally posted by 88GT-R
Thanks for the info, Simon. You covered the point on seal damage from using PAO`s and esters, but what would the effect be when using these base oils with the oil injection system? Is there any indication that the petroleum based oils burn cleaner than the Synthetics?
I use 2 stroke oil as premix and have recently started using 10w60 "fully synthetic" oil produced in Germany. Would this be a true synthetic, and what sort of base would it be?
Many thanks,

John
88 GT-R

John,

Synthetic oils actually burn cleaner than mineral oils as the molecules are of a uniform size.

I\'m guessing that the 10w-60 is Castrol RS which is a "hydrocracked" oil if this is the case. The premix is more than likely a synthetic if it\'s a bike oil.

Cheers
Simon

Hi Si,
The oil is not Castrol... It begins with an Mog... I can`t remember, and i can`t look as i am in Cyprus for a while:D

John
88 GT-R

Interesting reading, Mr Oilman!


So here\'s a question....API specifications on the back of the oil cans.....are these worth taking any notice of? I\'ve always tended to buy oils that have the highest API ratings. Do oils have to pass specific tests to achieve a specific rating.....and if they do, is this an indication of the quality of the oil?

Cheers,
Andrew

Thanks!

API Specs. You\'re doing the right thing. Current is SL so look for this as all specs are backwardly compatible.

These are them:

API = American Petroleum Institute
S = Service - Petrol Engine Performance
C = Commercisl - Diesel Engine Performance

PETROL

SG - Introduced 1989 has much more active dispersant to combat black sludge.

SH - Introduced 1993 has same engine tests as SG, but includes phosphorus limit 0.12%, together with control of foam, volatility and shear stability.

SJ - Introduced 1996 has the same engine tests as SG/SH, but phosphorus limit 0.10% together with variation on volatility limits

SL - Introduced 2001, all new engine tests reflective of modern engine designs meeting current emmissions standards

DIESEL

CD - Introduced 1955, international standard for turbo diesel engine oils for many years, uses single cylinder test engine only

CE - Introduced 1984, improved control of oil consumption, oil thickening, piston deposits an wear, uses additional multi cylinder test engines

CF4 - Introduced 1990, further improvements in control of oil consumption and piston deposits, uses low emmission test engine

CF - Introduced 1994, modernised version of CD, reverts to single cylinder low emission test engine. Intended for certain indirect injection engines

CF2 - Introduced 1994, defines effective control of cylinder deposits and ring face scuffing, intended for 2 stroke diesel engines

CG4 - Introduced 1994, development of CF4 giving improved control of piston deposits, wear, oxidation stability and soot entrainment. Uses low sulphur diesel fuel in engine tests

CH4 - Introduced 1998, development of CG4, giving further improvements in control of soot related wear and piston deposits, uses more comprehensive engine test program to include low and high sulphur fuelsSG - Introduced 1989 has much more active dispersant to combat black sludge.

One point about API specifications.

API specifications are minimum specifications for oils. They exist for your safety so that you have reasonable assurance that an oil will "adequately" protect your engine. However, these are not, by any means, a standard by which you could determine whether an oil was good or not.

As an example, you\'ll find that even a cheap oil which costs next to nothing will most likely carry the API SL rating. That should tell you something about how hard it is to attain that rating.

The other specs to look for are the European equivalent of API which are called ACEA. These are more stringent than API.

They are as follows.

ACEA Specifications
(Association des Constructeurs Europeens d’Automobiles)

ACEA ratings are prefixed with “A” for petrol, “B” for light or passenger car diesel and “E” for heavy duty diesel.

The current specifications are:

A1 Fuel economy petrol
A2 Standard performance level
A3 High performance and/or extended drain
A4 Reserved for future use in certain direct injection engines
A5 Combines A1 fuel economy with A3 performance

B1 Fuel economy diesel
B2 Standard performance level
B3 High performance and/or extended drain
B4 For direct injection car diesel engines
B5 Combines B1 fuel economy with B3/B4 performance

E1 Non-turbocharged light duty diesel engines
E2 Standard performance level
E3 High performance and extended drain
E4 Higher performance and longer extended drain
E5 High performance and long drain plus API performances

Too much deatail but anyway, at least you know now.

Cheers
Simon

Hey! There\'s never too much detail!!

Thanks for the comprehensive reply, though!


Do you have any opinion on non-named brands, such as Halfords, for example? I guess most people have shopped in places like this, and used their products. They obviously do not make their oil themselves, but buy it off of someone.....is there anyway to tell the quality of it?

Hey OILMAN I have a question, what are your views on using "Castrol R" on a high HP Rotary engine?
Do you know of its qualities as I have no clue but heard its quite good, and apparently it gives off a unique smell when the car is running, is this a myth?

QuoteOriginally posted by andrewrx7
Hey! There\'s never too much detail!!

Thanks for the comprehensive reply, though!


Do you have any opinion on non-named brands, such as Halfords, for example? I guess most people have shopped in places like this, and used their products. They obviously do not make their oil themselves, but buy it off of someone.....is there anyway to tell the quality of it?

I really don\'t like commenting on things like this as my views are normally biased towards quality oils.

How does made to a budget sound;)

Or if that\'s not clear enough

CHEAP:rolleyes:

If it\'s any consolation my knowledge of the industry is extensive and I wouldn\'t use them in my cars.

Cheers
Simon

hows about Motul 4100? would you comment on this :D

I think I\'ll be buying some this weekend so an experts view would be first class m8 ;)

Cheers

So Oilman are you able to answer the question on "Castrol R" then?

QuoteOriginally posted by BlitzBoy
Hey OILMAN I have a question, what are your views on using "Castrol R" on a high HP Rotary engine?
Do you know of its qualities as I have no clue but heard its quite good, and apparently it gives off a unique smell when the car is running, is this a myth?

I presume you mean the Castor based oils?

Yes they do have a nice smell!

However, they are all monogrades and will not suit the rotary.

Cheers
Simon

PS. The next post is usually someone who says they use them and they\'re fine:confused:

ahhh damn I would have loved to have used that oil if it did smell nice.

So what is a monograde?? sorry for the ignorance

QuoteOriginally posted by wiggy
hows about Motul 4100? would you comment on this :D

I think I\'ll be buying some this weekend so an experts view would be first class m8 ;)

Cheers

We like Motul and Silkolene here as they are brands that we sell and are top oils.

4100 is fine but the best (although not necessarily for the Rotary depending on who you listen to) are the Motul 300V oils, these like the Silkolene PRO Oils are truly 1st division!

Cheers
Simon

QuoteOriginally posted by BlitzBoy
ahhh damn I would have loved to have used that oil if it did smell nice.

So what is a monograde?? sorry for the ignorance

OH NO, I feel a long post coming on now!

Monogrades are single viscosity oils meaning that unlike a multigrade that operates at two viscosities, one when cold labelled "W" and one when hot (i.e. 10w-40 is 10w cold and 40 when hot) monogrades which are usually sae 30, 40 or 50 remain as this viscosity when cold or hot.

Have a read of this, it will explain:

What is this thing called viscosity?

It’s written on every can of oil and it’s the most important visible characteristic of an oil.

The viscosity of an oil tells you how it reacts in certain circumstances and how it performs as a lubricant.

When a oil is subjected to external forces, it resists flow due to internal molecular friction and viscosity is the measure of that internal friction. Viscosity is also commonly referred  to as the measurement of the oils resistance to flow.

There are two methods of viewing an oils resistance to flow. Firstly there is Kinematic Viscosity which is expressed as units indicating the flow of volume over a period of time and this is measured in centistokes (cSt).

An oils viscosity can also be viewed by measured resistance. This is known as Apparent Viscosity and it is measured in centipoises (cP).

However in the real world an oils viscosity is also referred to in such terms as thin, light and low etc. This suggests that the oil flows or circulates more easily. Conversly, terms such as heavy and high etc suggest the fluid has a stronger resistance to flow.

The reason for viscosity being so important is because it is directly related to the oils load-carrying ability - The greater an oils viscosity, the greater the loads that it can withstand.  (It must be added when new not over a period of time as all oils “shear down” with use)

An oil must be capable of separating the moving parts in your engine at the operating temperature. On the basis that an oils viscosity is related to its load carrying ability, you could be fooled into thinking that “thicker” oils are better at lubricating but, you’d be wrong in this assumption.

The fact is that in the wrong application a high viscosity oil can be just as damaging as using a low viscosity oil.

The use of an oil that’s too “thin” can cause metal-to-metal contact, poor sealing and increased oil consumption and conversely, an oil that’s too “thick” can cause increased
friction, reduced energy efficiency, higher operating temperatures, and poor cold starts in cold temperatures.

It is very important that you select the correct oil, not too “light” or too “heavy” and your Owners Handbook is a very good place to start as it lists the temperatures and options.

Oils thicken at low temperatures and thin as the temperature increases. The actual rate of change is indicated by their viscosity index (this number normally listed on the oils technical data sheet indicates the degree of change in viscosity of an oil within a temperature range, currently 40-100 degrees centigrade)

An oil with a high viscosity index, will normally behave similarly at these two temperatures but an oil with a low viscosity index will behave quite differently. It will become very fluid, thin and pour easily at high temperatures. A higher index is better!

Multi-grade oils are designed to perform at high and low temperatures by adding polymers to a base oil (5w,10w, 15w etc) which are heat sensitive and “uncoil” to maintain the higher viscosity sae 30,40,50 etc. This means that the oil can be used “all year round” rather than using different oils for summer and winter.
 
It is important to understand that the selection of the correct oil for your car is not just guesswork, you must consider the temperatures at which you need the oil to operate a 0w, 5w oil is better for cold starts as the oil circulates more easily when it’s cold and is able to flow around the engine more easily and quickly, offering protection at the critical moments following cold engine start-up. These oils are also known to give better fuel economy and engine performance.

Finally, all oils “shear” or thin down with use and this means that an oil that started life as a 10w-40 will with use become a 10w-20. The period of time this takes depends on the type and quality of the oil. The most “shear stable” oils are proper Synthetics, either PAO (Poly Alph Olefins) or Esters which have very high thermal stability.

They are in general of the more expensive variety but last longer and give the best levels of protection.

Don\'t say I didn\'t warn you! All clear now?

Cheers
Simon

I did originally plan to use Motul 300V but was put off by yout first post about esters etc being bad and possibly causing seal shrinkage :rolleyes:

Ahh well 300V it is then, what harm can in do in 3000 miles anyway, I always was one for trying things :eek:

ATF in the gearbox this weekend too :D

After your discussions above, would you be brave enough to list your, say, top 5-10 brands/specs that you\'d recommend for use in a rotary ?!;)

wiggy,

This is my opinion and my opinion only. I think 300V will be fine as it\'s a double ester and pao formulation. (Remember esters swell seals and pao\'s shrink them)

Even though we deal with Motul, I can\'t find out the percentages of each as oil companies treat their formulations with great secrecy, however as long as it\'s not 100% pao (which it\'s not) then they should counteract each other with regards to seals.

The Vicosities of 300V are 0w-20, 5w-30, 5w-40, 10w-40, 15w-50 and 15w-60. I would recommend 300V Chrono 10w-40.

I noticed you are a founder of GT4OC, have you read my posts on synthetics over there?

Cheers
Simon

Hi Simon

Its been a while since I\'ve been active on the GT4OC forum, I just stayed in touch with friends from there via e-mail, messenger etc.

I have had many a debate on there though about oils etc it just seems simpler on a std 4 stroke engine to rotaries :confused:

Did you ever read the barnies I had with people over ATF in the gearbox.....was funny after about 50 posts....not

I am going to do the same with the Rex though as it made a big difference on the GT4 in terms of losses through the gearbox. and the gear change seemed to improve.

Loads of car manufacturers now recommend ATF in manual boxes and its a better oil anyway by all accounts??

Know anything about this to shed some light on the matter??

QuoteOriginally posted by andrewrx7
After your discussions above, would you be brave enough to list your, say, top 5-10 brands/specs that you\'d recommend for use in a rotary ?!;)

Hell, that\'s one difficult question! Please don\'t let me get on my soapbox otherwise you\'ll never hear the last of me:o

Viscosity would be 10w-40 or 10w-50.

Brands in no particular order and based on quality alone would be

Silkolene
Motul
Fuchs
Castrol
Royal Purple
Amsoil

U.S. Oils sold in this country are too dear IMO and top European oils more than match for them so I recommend them as being better value for money as well.

Tin hat on and ready for a flaming, I\'ll get me coat:D

Cheers
Simon

QuoteOriginally posted by wiggy

I am going to do the same with the Rex though as it made a big difference on the GT4 in terms of losses through the gearbox. and the gear change seemed to improve.

Loads of car manufacturers now recommend ATF in manual boxes and its a better oil anyway by all accounts??

Know anything about this to shed some light on the matter??

I\'ll agree to disagree with you on this one. I would use an ester based fully synthetic 75w-90 in your box and diff. A good competition GL4/GL5 gear oil will outperform the ATF any day as it will be surface-active. On a decent one it will be GL4 but will have the superior GL5 load carrying capability.

There are two that spring to mind.

Silkolene SYN 5 75w-90
Motul Synthetic Gear 300 75w-90

Bear in mind these are competition oils so they\'re not cheap!

Cheers
Simon

Cheers for that...

When it comes to value for performance though, surely you must agree ATF is a good option? It costs next to nowt for a good Dexron III (castrol) compaired to a race quality gear oil.?

On my 4 I changed it every 5k miles because I could :D with it being so cheap and readily available

regards

I wouldn\'t disagree with the cost, a fully synthetic 75w-90 will set you back around £9-10 per litre. I would say it\'s a worthwhile investment though.

At the end of the day it\'s personal choice though.

Cheers
Simon

Hi Simon,
Cheers for all the info... but the question reference oil injection is still unanswered. In your experiance, would the breakdown of Fully synthetic oil when cumbusted, cause any more harmfull deposits than mineral oil?

John
88 GT-R

QuoteOriginally posted by 88GT-R
Hi Simon,
Cheers for all the info... but the question reference oil injection is still unanswered. In your experiance, would the breakdown of Fully synthetic oil when cumbusted, cause any more harmfull deposits than mineral oil?

John
88 GT-R

I have spoken to a chief oil chemist on this subject on many occasions and he has stated that this is simply not true.

If we are talking "true" synthetics, ester/pao they have less ash forming additives than mineral oils, they burn cleaner with less coking and deposits and are a superior lubricant.

He has worked on oils for rotary engines (and still does in special applications) and believes that they are more suited, not less.

Hope this helps

Cheers
Simon

Cheers, many thanks. The yank forums would be pretty chuffed with this info.

John
88 GT-R

I would be most interested to see how many of you here use synthetic oils and what they are.

I can do the research into whether they are petroleum or true synthetics i.e. ester,pao or ester/pao blends.

It may make an interesting and informative exercise.

Cheers
Simon

Motul 300V Chrono 10w-40 ;)  as of yesterday

Only 1. That\'s impressive.

Cheers
Simon

PS. Motul Tech data now on my website

Simon

Any word on that oil request I asked you about ;)

cheers

Wiggy,

My sole friend here! What request was that mate?

Cheers
Simon

Sorry, maybe I dreamt it :o

I told you I bought some Motul from Demon Thieves didn\'t I? I asked you for a price on some more, I like to have some spare for top ups and for my next change.

You also said you\'d send me a full price list :D

I\'m after 6 litres of the 300v Chrono 10W 40

cheers m8

Wiggy

YHPM matey!

Cheers
Simon

What a great thread! one day I\'ll try and understand it fully.

I\'ve not had too great an experience of oils, heard a few things in the trade though.  I worked for a rally team who were sponsored by Mobil, they sold off all the Mobil 1 that they got and bought in Castrol instead, they just couldn\'t get the oil pressure they wanted with Mobil 1 and didn\'t have alot to say about it.

I\'m new to rotarys and just want to know what oil I should use!?!

So there is no harm in using Castrol 10W 40 semi-synthetic from Halfrauds?

Mr. Oilman, I appreciate you sharing your knowledge with us, that\'s why we\'re all here isn\'t it?  What Silkolene would you recommend and can I get it from a local motor factors?

Thanks.

If you want a semi-syn the Silkolene XTR 10w-40 is as good as any.

If you want a top fully synthetic then Silkolene Pro S 5w-40, high ester content and very rotary friendly as it burns very cleanly.

I personally use fully synthetic in my RX8 and she runs far better on it with 40% lower oil consumption than with semi or mineral.

Based on what I know (from the oil chemists and questions to Mazda) there should be no seal compatability problems in most RX7 engines, especially if they have been rebuilt and I know many owners who use them without any issues at all.

Personally I would advise if your RX7 is modded or used on track then you would be mad to use anything other than a fully synthetic. Depending on power levels and oil temps etc a 5w-30 or 5w-40 would be the best viscosity range.

If the car is stock and street only then why not use a decent semi, changed every 3000 miles, it\'s not as good in the long run but it\'s probably cheaper, marginally!

Cheers
Simon

Cheers! that\'s a response I can read, take in, and remember without having to chuck out some old song lyrics from the memory banks :Hammer

Nice one, appreciate the help  :god