Mazda Rotary Club

I know you shouldn\'t use synthetic oils in rotaries.  What\'s the best mineral oil? To me puting something like GTX in my car is just frightening!!

If you want the absolute very best oil for your rotary then use Royal Purple synthetic.It is very very expensive.
The reason that Castrol GTX mineral oil is fine in your rotary is two fold.
1.The oil control rings in the sides of the rotors have "O" rings in them that are not compatible with SOME kinds of Sythetic oils.In other words if you want them to break down due to the chemical compostion of the oil destroying them then go right ahead,end result will be one very smokey engine!
2.A small proportion of the oil is fed directly into the engine for seal lubrication purposes and is therefore burnt in the combustion process,SOME synthetics tend to build up a sticky formation on the rotors through not burning properly and then start to stick the seals.

I do use synthetic oil in some race engines that I build but I also do not use Mazda "O " rings for the oil control rings.

Kind regards
Carl;)

Having just bought my Rex I made contact with my local Mazda garage. You can buy the mineral oil they recommend and put in RX-8s for £29.99 for 5 litres.

Sometimes it\'s worth going with what the manufacturers say.

Mart.

I use \'76 mineral racing oil in mine and seems to be very good. Roughtly equivalent in price to Mobil 1 synthetic but is mineral so rotary friendly (so I\'m told!).

I change every 3000 miles or so and check it regularily but my FD doesn\'t seem to use too much oil (and no water at all!) which is good!

Royal Purple now in stock, not on site yet.

I use Castrol Synthetic R 5/30W in my RX-8.

Synthetic ? Does the RX-8 not burn oil like the Rx-7 ???

They use the oil in the same way.

I think the benefits of a good Synthetic outway the costs.

Mind you, I would only recommend you run Synthetic in your RX-8 (or any RX for that matter) after you have a few miles on the clock.  I had done 10,000kms (6,000miles) before putting Synthetic in mine.

It\'s not so much the costs I was worried about, more the postings of people worried about deposits being left when the synthetic is burnt ! I guess you don\'t subscribe to that school of thought ?

Cheers,

Mart.

Hi Mart,

I didn\'t actually mean the $$$\'costs\' - just the opposite of \'benefits\'. :)

Like Carl has mentioned good synthetics/or the right type of synthetic won\'t leave a deposit.  I think that it also depends on how you drive the car, how often you change oil etc.

Most racing teams here use synthetic oil in their engines, some of course use pre-mix 2 stroke oil in the fuel tank which is another story...

It is up to the individual, I have found out here that some Mazda dealerships actually put synthetic oil in the engines/some use mineral.

Synthetic is a better oil - it is more expensive :)

I use Castrol 15/40w (i think) but its the stuff for conventional engines not the modern engine stuff.
Recently they changed it to Castrol high milage or something like that, now with "antiwear".
My question is, what effects will this anti wear have?

Also are there any effects changing to a different oil? I had read that you should stick to the oil you start using after an engine rebuild. Any truth to this.............

I use Castrol 15/40w (i think) but its the stuff for conventional engines not the modern engine stuff.
Recently they changed it to Castrol high milage or something like that, now with "antiwear".
My question is, what effects will this anti wear have?

Also are there any effects changing to a different oil? I had read that you should stick to the oil you start using after an engine rebuild. Any truth to this.............


Very interested to know what the experts think on this one.

This is a good read on oils.
http://ultimatejapcars.co.uk/forum//index.php?showtopic=3936&hl=

and another couple of gems of info.

Quote:

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, such as PRO S or PRO R. 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:

&

The post above written by John Rowland was originally posted by me on another forum with his permission. He is a very experienced Chemist (40 years with Silkolene) and his articles should be read carefully by all owners of powerfull cars as they are written by a Chemist not a Salesman!

He wrote an excellent 5 page article a while back called "Lubricating a Subaru" from which the following is an extract that all owners wanting to know about oil should read. I have his permission to post a part or all of it. I do not work for Silkolene but I am a Distributor of their products so his articles are of great interest to me.

Building a good oil.

It is impossible to make a good 5w-40 or even 10w-40, using only mineral oil. The base oil is so thin, it just evaporates away at the high temperatures found in a powerful engine that is being used seriously. Although there are chemical compounds in there to prevent oil breakdown by oxygen in the atmosphere (oxidation) they cannot adequately protect vulnerable mineral oil at the 130 degC plus sump temperatures found in a hard working turbocharged or re-mapped engine.

The answer to this is synthetics. They are built up from simple chemical units, brick by brick so as to speak; to make an architect designed oil with properties to suit the demands of a modern engine.

The synthetic myth

The word “synthetic” once meant the brick by brick chemical building of a designer oil but the waters were muddied by a court case that took place in the USA some years ago. The outcome was that the right to call heavily modified mineral oil “synthetic” was won. This was the marketing executives dream; the chance to use the word “synthetic” on a can of oil without spending much extra on the contents!

Most lower-cost “synthetic” or “semi-synthetic” oils use these “hydrocracked” mineral oils. They do have some advantages, particularly in commercial diesel lubricants but their value in performance engines is marginal.

TRUE synthetics are expensive and in basic terms there are three broad catagories, each containing many types and viscocity grades:-

PIB’s (Polyisobutanes)

These are occasionally used as thickeners in motor oils and gear oils, but their main application is to suppress smoke in two-strokes.

The TWO important ones are:

ESTERS

All jet engines are lubricated with synthetic “esters” and have been for more than 50 years but these expensive fluids only started to appear in petrol engine oils around 20 years ago.
Thanks to their aviation origins, the types suitable for lubricants work well from
-50 degC to 200 degC, and they have an added benefit. Due to their structure, “ester” molecules are “polar”; they stick to metal surfaces using electrostatic forces. This means that a protective layer is there at all times, even during that crucial start-up period. This helps to protect cams, gears, piston rings and valve train components, where lubrication is “boundary” rather than “hydrodynamic”, i.e. a very thin non pressure-fed film has to hold the surfaces apart.
Even crank bearings benefit at starts, stops, or when extreme shock loads upset the “hydrodynamic” film.

Synthetic Hydrocarbons or PAO’s (Poly Alpha Olefins)

These are, in effect, very precisely made equivalents to the most desirable mineral oil molecules. As with “esters” they work very well at low temperatures and equally well at high temperatures, if protected by anti-oxidants. The difference is, they are inert and not polar. In fact, on their own they are hopeless “boundary” lubricants, with less load carrying ability than a mineral oil. They depend entirely on the correct chemical enhancements.

It is a fact that “PAO’s” work best in combination with “esters”. The “esters” assist load carrying, reduce friction and cut down seal drag and wear, whilst the “PAO’s” act as solvents for the multigrade polymers and a large assortment of special compounds that act as dispersants, detergents, anti-wear and anti-oxidant agents, and foam suppressants.
Both are very good at resisting high-temperature evaporation, and the “esters” in particular will never carbonise in turbo bearings even when provoked by anti-lag systems.

So, in conclusion, Ester gives the best protection and Ester/PAO combinations have great benefits because they work well together. They are more expensive but worth it if you wish to do the best for your engine.

Been using Red Line polyol ester oil for last 35,000 plus miles, no problems, no regrets.  My engine is fairly highly modified, hence why I don\'t use (won\'t use) dinosaur juice (sorry, mineral oil).  

I agree that some synthetics are garbage and will gum up rotary engines.  Probably, they are none too good for piston engines either.  Equally, on a standard rotary engine, there probably aren\'t many technical arguments for using synthetic rather than a mineral oil.  

Personally, when you see how many people have had positive experiences with good quality synthetic oils and the rotary engine, I wonder why the story persists that these oils are \'bad\' for rotaries per se .

Peter

Now here\'s a questions - I use Motul ester synth oil in my highly stressed KTM single cylinder 4 stroke. How would the FD3S fare with something like this? Also, would there be any benefits/problems arising from the use of fuel mixed with Motul ester sunthetic 2 stroke oil at say 100:1. In my 2 stroke KTM enduro bike I have absolutely zero carbon build up on rings and piston crown.

This is getting a bit too technical for me ...... Pip told me to use 76Motorsport oil and to change it every 3000mls, so thatts what I do:)

Oh! I seem to have a stutteter;)

QuoteOriginally posted by Carl
1.The oil control rings in the sides of the rotors have "O" rings in them that are not compatible with SOME kinds of Sythetic oils.In other words if you want them to break down due to the chemical compostion of the oil destroying them then go right ahead,end result will be one very smokey engine!

Does you know what compund it is that damages the O rings or what the standard Mazda O rings are made of?  I have a few relatives in the petrochemicals industry, and specifically one in the US dealing with oils, whose advice I would like to get.  

A good quality synthetic with a PAO basestock will handle heat much better than a conventional oil can so would be the way to go, but without knowing the answer to the question above, selection would seem to be pot luck - other than choosing a decent oil like Repsol, Motul, etc.