Upgrade engine oil?

Just wondering what people use in their cars. Is it vital to stick with the Elf recommended oil or is it cheaper/much better all round to use some of the more common performance brands?

Also is it really a no no to top up with a different oil brand even at the same grade?

Mixing oil brands should be no problem at all. Just never mix synthetic and mineral......because they dont!(mix).
I use Valvoline semi synthetic...cant remember the grade but it does the job.

Mobil 1 for me, around the £30 mark for one can though.

But its a bit dear as you need 2 cans and it only comes in 4 litre cans, so you only get a litre left to top up with

Im changing to Triple R Synthetic next time, its only £17.99 for 5 litres in BIG W (Woolworths) and its recommended by Lotus. Cant be bad.

[Alpineandy]

I'd heard that you shouldn't use Mobile 1 in a turbo as it's so thin that it gets sucked into the turbo as soon as any wear appears.

Maybe I mis-heard.

On my A310s I use 20/50. This is a 70s engine which was designed with bigger tolerances than 80s (and later) engines.

If your engine has a high milage then I'd strongly suggest 20/50.

Either used high quality stuff OR change it very regularly.

[stephendell]

Andy's right.

Bizzarly Mobil 1 is not ideal for the GTA Turbo and is better suited to the Atmo. Even then it's too thin and can cause all sorts of problems.

The PRV engine is an old design (2 valves per cylinder, single cam per bank, timing chains, generous tolerences etc etc) and doesn't need an expensive hi-tech oil. A decent multigrade from a well known brand is all you need.

Your GTA will be perfectly happy with something like Castrol GTX 15-40W. (Or even 20-50 for the noisy high milers out there). Available cheaply by the litre so no wastage either.

Alternatively buy some Motrio oil from your Renault main dealer.

Don't waste your money on expensive synthetic oil unless you're running a highly modified or multivalve engine conversion.

If you insist on sticking with Mobil 1, buy it in France next time you're over there. It's at least 50% cheaper in the hypermarkets and is also available in 2L cans.

The V6 turbo is a problem really. All turbo cars should have pissy thin oil, because the phosphur bronze bearings in the turbo have massively high tolerences to enable their operation and reliablilty, but yes, the engine needs something thicker.

Think you will find there are 2 grades of Mobil 1 .... the 0W/40 stuff which is to thin for turbo cars but theres also a 15W/50 motorsport with added supersynTM(!?!), this stuff is like gold dust though so i tend to buy a bottle if i ever see it in halfords ...

There are, in fact, as previously stated two mobil 1's. Some years ago I put Mobil 1 in my car because at the time I couldn't obtain Valvoline 20/60 synthetic. My car always runs at 3 bar ticking over and 6 bar running. With mobil 1 my tickover dropped to 2 bar, very worrying. I mentioned this to the garage, they then informed me that there was another mobil 1 called mobil 1 racing. It is no dearer than the ordinary and since installing this the engine is now running at its correct pressure.

[stephendell]

Actually there are six types of Mobil 1 for road use, even before you get onto the racing formulae.

The two previously mentioned are those most commonly available.

They are sold under various guises e.g. longevity formula, performance formula etc

See http://www.mobil1.com/products/trisynth/index.jsp for more details.

I have been advised by 2 turbo manufacturers and Subaru themselves not to use Mobil 1 as it is so thin it will actually make the car burn oil where oil can seep thru the seals in the turbo into the exhaust system, and have actually had this happen on my GTA before. When I had my Legacy turbo Subaru said they didn' trecommend Mobil 1 and that a 5W 50 oil was their recommended lubricant.

[Alpineandy]

I think the oilman (member 137) would be the best person to talk to about engine oil. He's been in great demand on the pistonheads forum for his technical knowledge.

Interesting topic. I ran Mobil 1 for years with no apparent problems, but none-theless interesting comments about Mobil1.

Currently I am using Castrol RS - 15W/50 Racing.

Not having had the engine apart, I couldn't possibly say if it's any good 'though.

I think the oilman (member 137) would be the best person to talk to about engine oil. He's been in great demand on the pistonheads forum for his technical knowledge.

Hello chaps,

There are only two Mobil 1 grades commonly available in this country and that is the 0w-40 and the 15w-50, the 0w-40 will be way too thin for these engines, the 15w-50 on the other hand will be fine. It is a common misconception that synthetic oils are too thin, this is untrue as synthetics come in the same viscosities as mineral and semi.

As your engines are of older design a thicker oil is preferable, however a 20w-50 is slight over kill, the 20w will provide very poor cold start protection (80% of when engine wear occurs) so moving to a 10w would be better and as thin as I would go for these cars.

There will always be gaines from using a full synthetic. As synthetics were not freely available when the car was built a semi or a mineral was recomended, but these days you can use better.

If it was my car I would be using a 10w-50 PAO/Ester (no petroleum base stock) fully synthetic oil.

Esters assist the additive pack in a motor oil formulation because they are surface-active (electrostatically attracted to metal surfaces), so they help to reduce wear and friction.

They are fluid at very low temperatures and at high temperatures they are very chemically stable and have low volatility (don’t evaporate away).

They also help to prevent hardening and cracking of oil seals at high temperatures making them ideal for tuned turbo engines.

Hope this helps.

Cheers

Guy.

[Alpineandy]

Thanks Oilman.
This now opens a can of worms over what is PAO or Ester based or what is 'hydrocracked' etc..
cheers

Hopefully this goes someway to explain.

A word of caution – You get what you pay for!

Below is an article written by John Rowland, Silkolene/Fuchs Chief R & D Chemist for 40 years.

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:

Cheers
Guy