The reasons synthetic oils are better

[banned advertiser]

Hi Simon
You did start the post, and for posting I apologise.
Regards
Gary

[oilman]

No problems mate, no offence taken

Cheers
Simon

[Jake]

I don\'t wish to pee on anyones bonfire but I did start this thread.

RP is not the only oil in the world chaps, good maybe but there are plenty of other decent synthetics that are as good if not better in some cases.

I\'ve been on this forum for a while now and yes I SELL OILS!

There are some very decent European Synthetics that Chemically are a match or better than RP, I have the analysis and comparisons of the quality (I have had them tested including RP) so don\'t think that you don\'t have a choice.

We use the Silkolene Pro S 5w-40 in the Dragon car because of its quality and use Motul 300V 5w-40 and 10w-40 in many highly modified RX7\'s 450bhp plus.

You don\'t have to pay £50 for 5L of oil when the likes of Silkolene and Motul are a little over £40 for 5L, expensive compared to GTX I know but they are not the same thing. One is boggo standard mineral oil and the other is ester/pao synthetic (manmade) not dug out of the ground!

Cheers
Simon

Not wanting to start a whole \'my oils better then yours\' debate but I\'d be really interested to see an analysis of different oils possibly accompanied by descriptions of what each figure means in real terms.  There is so much talked about oils it\'d be nice to see some data as I find this whole debate really interesting, especially given how important oil is to an engine.

[ro284]

JAKE There is so much talked about oils it\'d be nice to see some data as I find this whole debate really interesting, especially given how important oil is to an engine.

Me too Jake, even after all this i\'m still hesitant to change from mineral, (i used Mobile 1 in my Scorpio,) while i can understand that in the crank-case, lubricating bearings e shaft etc, oil is oil! (and the better quality the better protection) and i can understand that synthetic may well better withstand the high temperatures in a Rotary, i seem to have it deeply entrenched in my mind (don\'t know where that came from!) that the synthetic does not burn (as in clean no sticky deposits burn!) so well when used for lubrication in housings and Apex seals, i am even concerned that if it does not burn so well, it may foul up the plugs! perhaps i should wait for even more info before changing to synthetic, but try a synthetic premix and see how it goes from there. Bit more convincing needed for me.
cheers Bob

[oilman]

I put Clive\'s question to the man in the know John Rowland (Silkolene\'s Chemist for more than 40 years) and he has given this reply which I am posting in full.

He has also agreed to write an article regarding synthetics in rotaries for both the Forum and the Club Magaizine (in more detail) although don\'t expect it tomorrow as it\'s a lot of work!

Quote: John Rowland (Silkolene Chemist)

Regarding seal tip to chamber wall’ contact, the fact that people feel that there must be actual contact shows that they don’t know what is really happening! It’s no different from piston ring action in normal 4-stroke engines. Except at the top and bottom of the cylinder bore, where the ring is stationary for an instant, the velocity of the ring generates a ‘wedge’ of oil which floats the ring off the bore surface by a few thousandths of a millimetre, preventing metal to metal contact, and reducing wear to virtually zero. (Hydrodynamic lubrication.) That’s why modern 4-stroke motors last so long! In fact, the oil helps the ring to hold compression and prevent blow-by.

In a rotary, if a perfect oil film could be maintained on the chamber walls, seal and chamber wall wear would be negligible and compression actually improved, giving better efficiency and long component life up to or even better than 4-stroke piston standards*. Unfortunately, the severe conditions in a rotary with most of the chamber walls being exposed to hot gas means that this ideal situation never exists, but a top quality synthetic lubricant with superior temperature resistance goes a long way towards achieving this ideal.

*There is a type of rotary compressor, the ‘Hydrovane’ where the compression (up to 9 Bar in some versions) is achieved by running an offset rotor with 6 or 8 sliding seals or vanes in a more or less circular chamber. The whole thing is oil-flooded. The seals are hard cast iron, and the chamber casing is SG iron. All very basic; no fancy materials or hard coatings. These things run for 5000hrs a year for 20 years, all because hydrodynamic lubrication is preventing seal to chamber wall contact………..and they do get hot! Localised temps of 250C at the high compression side.

Unquote: John Rowland (Silkolene Chemist)

Cheers
Simon

[oilman]

To identify the quality of an oil there are figures outside of a normal technical data sheet that are important. The key ones being the HTHS number and the Noack %.

These figures are the best indicator of basestock quality and therefore shear stability of the oil, stay in grade performance for want of a better description.

High-Temperature/High-Shear

This test is a simulation of the shearing effects that would occur within an engine. In fact, it\'s actually designed to simulate motor oil viscosity in operating crankshaft bearings.

Under high stress conditions where shearing can occur, the VI Improvers (polymers) break down. As they do, the viscosity of the oil decreases. This is what the High Temperature/High Shear test checks for.

The HT/HS test is measured in Centipoise (cP) as the Cold Crank Simulator test is. However, in this case, because you\'re hoping for the least loss of viscosity with an increase in heat and stress, you want the cP value to remain high.

Each SAE multi-viscosity grade has a specific lower limit for the HT/HS cP value. If a multi-viscosity oil cannot achieve a cP value above that limit, it cannot be classified under that viscosity grade. For instance, according to the SAE specifications, an oil must achieve an HT/HS cP value of 3.7 or higher in order to be classified at the 15w40 viscosity grade. The thinner the oil the lower the number.

Noack Volatility Test

The NOACK % is also an important number as it tests for the % of evaporation at 250 degC and therefore indicates quality of basestock and strength. This is used to test the oil consumption figures based on evaporation, quality basestock are more thermally stable and therefore have lower evaporation % figures.

Good low viscosity synthetics should be around 5 to 7% the ACEA max allowed to make the A3 rating is 13%. Many oils are formulated to meet this number i.e. pass!

So, the HIGHER the HTHS and the LOWER the NOACK % the better the oil quality in simple terms.

Some oils with good numbers are as follows:

Silkolene PRO S 5w-40
HTHS 4.07
NOACK 6%

Motul 300V 5w-40
HTHS 4.51
NOACK 7%

Motul 300V 10w-40
HTHS 4.19
NOACK 7%

Motul 8100 5w-40
HTHS 3.92
NOACK 8%

Ok, granted that these oils have top quality basestocks and therefore better results in these extreme tests but as an example of other well known synthetic oils that are built to meet the minimum standards, here are some so don\'t be fooled!

ACEA pass for HTHS on 5w-40 and 10w-40 is 2.9 and for NOACK is 13%

These oils all show 2.9 and 13% (the requirement for a pass of ACEA A3 performace rating)

Shell Helix Ultra 5w-40, Valvoline Syn Power 5w-40, Mobil Synt S 5w-40

There are many more but it merely indicates that these oils are built to pass a spec and nothing more. A spec that is intended for stock road cars not modded or highly stressed track cars, there is a difference!

Cheers
Simon

[Jake]

Excellent post, very informative.  I don\'t know if you have it but I\'d be very interested to see the same information on 76 oils, Royal Purple and any others that you have info. on.  I\'d understand if you don\'t want to post this up given that different vendors stock different oils and it might turn the whole thread into a bit of a \'my oils better than yours\' argument but I think it\'d be really helpful to forum users.

[oilman]

I do not have comparable figures for Royal Purple and I have checked their website for HTHS and Noack numbers but to no avail.

The 76 5w-40 (it is a ConocoPhillips oil) has the following numbers HTHS 3.8 Noack 13% I suspect based on these numbers that is a hydrocracked (petroleum based synthetic, not a proper man made one)

I do have chemical analysis from 2005 on a Royal Purple 10w-40 but it would be unfair to post the details here. You can always email me.

Cheers
Simon

[oilman]

Whilst on the subject of that buzzword synthetic, here is something that explains why the word synthetic means absolutely nothing unless you can clarify "what" synthetic you are talking about! Not all is equal in the world of oils, it\'s a minefield but that\'s why I am here - To help!

Quote: John Rowland (Silkolene Chemist)

Costs of synthetics vary considerably. The most expensive are the “Ester” types originally only used in jet engines. These cost 6 to 10 times more than high quality mineral oils.

The cheapest synthetics are not really synthetic at all, from a chemists point of view. These are in fact specially refined light viscosity mineral oils known as “hydrocracked”. These have some advantages over equivalent mineral oils, particularly in lower viscosity motor oils such as 5w-30 or other oils with a low “W” rating such as 5w-50 etc and they cost about 1.5 times more than good quality mineral fractions.

We use several different grades of this base oil, where appropriate. This is the “synthetic” which is always used in cheap oils that are labelled “synthetic”.

Yes it’s a cruel world, you get what you pay for!

Now, you may ask, why are these special mineral oils called “synthetic”?

Well, it was all sorted 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 wet their knickers with pure delight!
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.

So, the chemistry of “synthetics” is complex and so is the politics!

The economics are very simple. If you like the look of a smart well-marketed can with “synthetic” printed on it, fair enough, it will not cost you a lot; and now you know why this is the case.

But, if you drive a high performance car, and you intend to keep it for several years, and maybe do the odd “track day”, then you need a genuine Ester/PAO (Poly Alpha Olefin) synthetic oil.

This oil costs more money to buy, because it costs us a lot of money to make, very simply, you always get what you pay for!

Unquote: John Rowland (Silkolene Chemist)

A veritable minefield thanks to a US Court ruling!

Cheers
Simon

[clive]

Appreciate the myth explosion and that is why I have got involved, and I fully understand the fact that you need wall lubricant on ANY engine indeed I have worried that if you have too much fuel pumping into a Rotary that you could end up with "bore wash" but will readily admit that I do not know whether with modern synthetics this even actually a problem especially if its not petroleum based oil.

It is going to be a difficult thread and long thread because we will not only end up wanting to know why some synthetic oils are not compatible and not others, if nothing else because of oil seal destruction in Rotary\'s,  but also this will unfortunately lead to MRC needing to know the brands of synthetics that are "useable"

One thing I have keep up my sleeve is the reason that I personally have run with the "just put mineral oil in" to members.

The reason is that it keeps it simple telling members to fit mineral as the last thing as a club that we could have is a recommendation from us to pour any oil be it synthetic or otherwise into their engine knowing that some are not compatible.

As with my previous post I know that there are distinct advantages from using synthetics the, however we will always come back to the "which ones question"

[RobbieRX-7]

I do have chemical analysis from 2005 on a Royal Purple 10w-40 but it would be unfair to post the details here. You can always email me.

Cheers
Simon

Please post simon, as im sure everyone want to know. Could you not compare the 2005 royal purple 10w-40 Noack Volatility Test and the HT/HS  test results with the 2005 silkolene/motul 10-w40 oils to make it more fair?

Also i wonder if gary has these deep anaylisis results being as he is stocks royal purple products? If so then please post them gary

[Adriansturgess]

This is obviously a very technical and complex subject...It would be ideal if the MRC could distill all this technical information down to a simple oil recommendation chart for engines in various states of tune from stock to stonkers :p  I am sure most of the technical jargon, impressive as it sounds, goes over most peoples heads and all they really want to know is \'which oil is going to be best in my engine\'. Cost will also play its part of course. I can forsee that MRC will get into awkward territory if it starts recommending one brand over another, which is a shame from members point of view because we really want to know which oil is best for our cars. I\'m pretty much converted to the idea of synthetic but I still don\'t know which oil to go out and buy as the best compromise between cost and performance.

[vxer]

This is obviously a very technical and complex subject...It would be ideal if the MRC could distill all this technical information down to a simple oil recommendation chart for engines in various states of tune from stock to stonkers :p

Good idea! Gets my vote...  :Thumbs-up

[oilman]

Ok, to be fair here I can do what you ask but of course can only recommend the oils that I sell!

My recommendation would be as follows:

Highly modified / tracked etc = Silkolene Pro S 5w-40, Motul 300V 5w-40 or 10w-40

Mildly modified / street = Motul 8100 5w-40 or Fuchs Titan Supersyn SL 5w-40

Stock / street = Fully Motul 8100 5w-40 or Fuchs Titan Supersyn SL 5w-40
                    = Semi Silkolene or Fuchs XTR 10w-40 or Motul 6100 10w-40

Personally I would not recommend mineral oils at all even though I sell them.

Suffice to say there is nothing wrong with using the likes of Silkolene Pro S 5w-40 in a stock street car, it may just be overkill but your engine would certainly appreciate a drop of the good stuff. Just don\'t go using the cheap stuff if the engine is highly modified or used on track, it\'s simply not built for the job.

Gear oils, we tend to recommend the Silkolene SYN 5 75w-90 fully synthetic for both gearbox and diff but you could use a semi synthetic the likes of Fuchs Titan Gear 75w-90 or Castrol Syntrax 75w-90 in the box and a dedicated LSD oil (if required) in the diff like Silkolene Boa 90LS or Motul 90PA. Once again, remember modded/track cars put more stress on the box and therefore you will be better using a decent fully synthetic in these cases.

Finally if the car is N/A then it will put less demands on the oil than a turbocharged one in which case you could get away more easily with a semi-synthetic. If turbocharged fully is always a better option.

Cheers
Simon
http://www.opieoils.co.uk

[banned advertiser]

Royal Purple 10w40 has a HTHS of 4.05 cant find NOACK
I have asked RP for these, I\'ll wait and see.
HTHS is mentioned on the pdf from there site.

I said in a very early post on here which Clive removed.

"Like prefered tuners, ones not always better than another, poeple have prefered oils, this will influence what they buy.

Some will stick there heads in the sand and because Mazda used information thats now 25 years old, will say "if it\'s not broke don\'t fix it".

How many guys with RX7\'s will be here in 2 years time, with the constant turnover of cars being sold, those may just say nutts, cheap will do, I wont have it come engine build".

It would be a good idea for a list providing people dont too hung up on whats best, sometimes there is little point putting a RP race oil because its better than RP 10w40 beacuse the car is not used in such a way that it will benefit from it. Same Im sure applies to Silkolene, some of there grade oils far outstrip the quality needed for some cars.

MRC does have to be carefull, Clive is also a vendor who sells 76 Oils, so to a degree has a vested interest in members buying mineral or 76, and has recommended that people who want to save money go to Asda and buy it. I know I wont put oil in my car that I can buy for £2.75 a drum. So cant see that in the clubs interest to recommend.

If a list has to be made, and MRC have to get involved, why not just put a list of oils that MAYBE (cause you will never prove it) wont harm, because it will be a hard job to list and state reasons why.
If MRC keeps out of recommending then it will be down to the vendors to recommend and face the outcome. If Clive wants to act as a vendor and put forward 76 Oils tech in a SHY thread thats cool, each can state there qualities, and let members decide but not to say the club recommends, as its not the club, its the club president and vendor telling all to use mineral.

So what if the HTHS number is .05 better, it will still be good enough.
Sometimes there is too much confusing information.
Its good to read techy posts, and Simon has a wealth of knowledge, cant take away,

I enjoy Simons threads. Just trying to put a balance on it, as Im none technical.

If any of this upsets Simon then please remove, posted as a couple kinda asked about RP. Im not getting in to my oils better than yours.