Engine Oil

[Walshy]

Having spoken to several different people I am non the wiser.

As per usual, everybody has there own ideas on the most effective oil to use.

Bearing in mind the engine isn't the most advanced piece of kit on the planet, I can't see the benefit of buying extremely expensive brands.

Some run full synthetic, most run semi-synthetic. Some run standard oil. All seem to be of the opinion that 10W/40 is the must.

I always ran a standard 10W/40 standard GM oil and then several people at the last round said that they seemed to find that this Castrol Magnitec 10W/40 semi-synthetic is the nuts.......

I know there are good and bad oils, but can it really make that much of a difference. I understand about the thinning of theoil as it gets hotter etc, but what does everyone else run??????

I thought I might try this Magnitec stuff going off the good reviews it's getting.

[ACE Motorsport]

After much study of oils used in race engines, I have come to the following conclusion.
When a race engine has just been rebuilt, all the moving parts need bedding in, use a cheap oil that will keep everything cool but will allow the metal parts, rings etc, to wear in. Once everything has had a chance to bed in, about half an hours driving, I then use fully synthetic oil, as this gives maximum engine protection and virtually no engine wear at all.
10w/40 is fine, 10w/50 is better.
It is vital to observe the oil pressure at all times, and the temperature should be monitored too, between 80 and 100 centigrade is about right.
Of course everyone has their own preferences, this just seems to work on the race engines I have worked on.

[ss_collins]

goona give this a go in racecar engineering

[Adam43]

Here is a previous thread on the matter: http://tentenths.com/forum/showthrea...&highlight=oil

Everyone does have their own preferences as ACE M says. If we are talking road car based I agree with what he says (I know little of brand new racing engines). In the other thread you see people who use really thick stuff in older engines.

We have just changed engines this year from 6 cylinder to 12 and our starting point is Magnitec. It takes a lot of the stuff too, but for an extra few pounds I felt it was worth it.

[R59]

I always run my engines in on a ordinary mineral oil, then change to a good synthetic. I used Mobil 1 on my Vauxhall engines, and wear was very very small.

I'm going to try some Penzoil 5W40 Synthetic in my Chevy, just to see what it's like. The price is reasonable, and an American oil in an American engine ought to work!

Don't forget the cooler too....

Adam - just a thought - I know I've asked before - have you got a spare XJS cooler laying around yet??

Rob.

[zefarelly]

straight mineral for an hours bedding in, and either Millers or 76 for racing both 20/50 for old Ford engines, it tends not to stroll past the rope oil seal !

[Richy_Rich]

I've use both millers and penrite 20w/50 in my rattly old spitfire. I found the penrite to be marginally better, but more difficult to get hold of round my way.

[Adam43]

sorry off topic folks...

Originally Posted by racing59

Adam - just a thought - I know I've asked before - have you got a spare XJS cooler laying around yet??

I'm afraid not. In the end I picked up an aircraft oil cooler (it is lovely!). The standard ones do go and are quite rare unless you buy new (which is relatively expensive). Try ebay (!), although most Jag coolers that come up on their tend to be XJ40. You could try scrappers, but you'd be lucky to find a good one. We did buy another car (scrapper) since we last spoke, but the oil cooler had been damaged.

back on topic...

Originally Posted by zefarelly

straight mineral for an hours bedding in, and either Millers or 76 for racing both 20/50 for old Ford engines, it tends not to stroll past the rope oil seal !

Yes a problem on older engines. The equivelent seal on the XK engine allows this.

[zefarelly]

Yes a problem on older engines. The equivelent seal on the XK engine allows this.[/QUOTE]

the newer ones seem to be coated with something teflonish and are a lot better, they don't seem to leak for as long as the engine stays together !

[Wingman]

First off, I have absolutley no experience with racing engines, but I recently had the 5 litre V8 in my Holden rebuilt. I'm a mechanic, but the actuall engineering work was done by a guy who really knows his stuff. I had a long chat to him about oils and he warned me against running synthetic oils in anything that has roller bearing surfaces, because basically it is too good, and the surfaces slip instead of roll, and this causes masive heat build up and burns the bearings. I can understand this, as we had similar experience with Moly Grease a few years ago. This stuff was the "ducks guts" in grease and we used it in everything. Then we started getting wheel bearing failures, and on investigation, they were burned from not rolling. Needless to say Moly grease is not seen anymore.
Hope this is some help.

Cheers.

[dtype38]

Some interesting points in this thread... I think the most important one being:
You need to use the appropriate grade and type of oil for the age and type of your engine. Some may need 10W40 fully synthetic, some 20W50 mineral like mine, and the best starting place is what the manufacturers original handbook suggests for that engine. This will tell you what the designers, with many hours of running in all sorts of conditions, think works best. Its far better advice than just asking around! Give it a try. Then, if you have a specific problem with temperature, or wear (and this all depends on the type of racing you do) then take expert advice on which way to adjust the grade to solve that particular problem.
Modern synthetics are great for modern engines, but like has been said above, you can't run-in a rebuil engine with them, and... they don't seem to take kindly to being burnt. Beware putting them in engines old enough to have been designed to allow a bit of bore bypass to lubricate the upper rings. Adam, not sure if you've got a 5.3ltr or 6.0ltr, but in my personal experience the 5.3 V12s are happier on standard GTX than Magnatec.

[Adam43]

Good general advice there dtype38.

It is a 5.3, pre-HE. We ummed and ahhhed on this and in the end probably went a little against your general advice. It is GTX Magnetec for convential engines. We decided that it didn't make much difference, although at the moment the engine is never getting run for long periods so the sales pitch of "protecting from the moment you turn the key" did it!

[dtype38]

Yeh, I understand where you're comming from on that one. I agonised myself over exactly the same decision. In fact I did ask advice from an automotive oils technician who used to go to our local JEC club meetings. He said that the currently available GTX is actually a much higher quality and more duarble than the GTX that was available when the pre-HE 5.3s were being made, so he didn't see any need to upgrade further.

To illustrate the point futher, I tried Castol RS 10W60 in my current XK3.8 engine. Very expensive and supposed to be the dogs danglies for older engines..... and it was rubbish. Constant overheating problems and low oil pressure issues. On the advice of a man with some practical expericence I replaced it with Valvoline 20W50 Racing mineral oil. Hey presto, everthing worked fine

On a related point, I would never advise a lower grade of oil for financial reasons. My sump takes two gallons of oil and on Castrol RS, that's quite a few £££'s worth, but it's still pennies compared to the value of the engine. Next time you're looking at Halford's shelves and thinking "Ohhhm this one is only £7 a gallon!" just think to yourself how much a full set of main and big end bearings are going to cost to buy and fit!!

[Tim Falce]

I ran my original race engines on cheapo oil, Comma 20-50 which is probably the same stuff as Halfords and all the other supermarket oils. I never had any problems with bearings or general wear although I made sure I changed it often.
The only time I had any bearing failure was when using a good quality semi synthetic in a "so called" professionally built race engine although that could have been down to bad workmanship and not oil but I will never know.
Now using Valvoline and so far I have had no trouble and that is after a seasons racing and I still get good oil pressure on tickover when the engine is hot.

[graham blackwell]

I've just switched from Mobil1 0W40 to 76 Racing 5W30, bought from www.aaoil.co.uk and its actually cheaper than Mobil1 and so far, oil pressure climbs much quicker at startup due to the better grade when cold. They stock a good range of synthetics, and should have something to suit everybody.

[graham bahr]

basically the real important thing is that the grade oil suits the bearing clearances, modern engines on thinner oils generally have tighter clearances and tolerances and therefore like thin oils, thin oils in old engines tend to leave you with low oil pressure.

in all my race engines except my current one i have always used reasonable quality normal oils, as theres no point in paying extra for an oil that should last tens of thousands of miles when it gets drained out after a few races, and i've never had problems with engine wear.

my current engine is an exception, thats on mobile 1 but only because its turbo charged and in any case when the crank was ground it was done to tha tighter clearances spec'd for that later e30 m10 engines rather than the early 2002 m10 engines, although they are the same engine