Lubricating a modded or track car, some advice

[oilman]

If you are "modding" your car and adding BHP or using it on track then consider your oil choice carefully as the stock manufacturers recommended oil will not give you the protection that your engine requires.

A standard oil will not be thermally stable enough to cope with higher temperatures without "shearing" meaning that the oil will not give the same protection after a couple of thousand miles as it it when it was new.

Let’s start with the fundamentals. An engine is a device for converting fuel into motive power. Car enthusiasts get so deep into the details they lose sight of this!

To get more power, an engine must be modified such that it converts more fuel per minute into power than it did in standard form. To produce 6.6 million foot-pounds per minute of power (ie 200 BHP) a modern engine will burn about 0.5 litres of fuel per minute.(Equivalent to 18mpg at 120mph). So, to increase this output to 300BHP or 9.9 million foot-pounds per minute it must be modified to burn (in theory) 0.75 litres.
However, fuel efficiency often goes out of the window when power is the only consideration, so the true fuel burn will be rather more than 0.75 litres/min.

That’s the fundamental point, here’s the fundamental problem:

Less than 30% of the fuel (assuming it’s petrol) is converted to all those foot-pounds. The rest is thrown away as waste heat. True, most of it goes down the exhaust, but over 10% has to be eliminated from the engine internals, and the first line of defence is the oil.

More power means a bigger heat elimination problem. Every component runs hotter; For instance, piston crowns and rings will be running at 280-300C instead of a more normal 240-260C, so it is essential that the oil films on cylinder walls provide an efficient heat path to the block casting, and finally to the coolant.

Any breakdown or carbonisation of the oil will restrict the heat transfer area, leading to serious overheating.

A modern synthetic lubricant based on true temperature-resistant synthetics is essential for long-term reliability. At 250C+, a mineral or hydrocracked mineral oil, particularly a 5W/X or 10W/X grade, is surprisingly volatile, and an oil film around this temperature will be severely depleted by evaporation loss.

Back in the 1970s the solution was to use a thick oil, typically 20W/50; in the late 1980s even 10W/60 grades were used. But in modern very high RPM engines with efficient high-delivery oil pumps thick oils waste power, and impede heat transfer in some situations.

A light viscosity good synthetic formulated for severe competition use is the logical and intelligent choice for the 21st century.

Cheers
Simon

[dace]

So Simon, I know this a loaded question, what is your recommendation..................

[oilman]

I have had my wrists slapped for selling here before so best to contact me off the boards and I will give you a recommendation. My website is a good place to start.

Cheers
Simon

[dace]

PM sent

[SteveH]

Impressive stuff, I take it you dont work for Flora

From a complete Oil Novice like myself, what do the grades actually mean? Clearly a measure of viscosity, but I would be interested on what scale etc??

[dazzer]

Have you read the sticky in Audi Tuning and Modifications

[harry]

Allow me, sir...

http://www.rs246.com/index.php?name=PNp ... ic&t=53088

[MCB]

I asked the proprietor of an excellent tuning firm this question and he recommended using Castrol RS 10w/60w, anybody using this?

[DavidT]

I asked the proprietor of an excellent tuning firm this question and he recommended using Castrol RS 10w/60w, anybody using this?

Good question, especially if the car does say 4600 road miles and 400 track miles between changes, is this still the best oil ?

[MCB]

Found this post regarding 10w/60w oil: http://www.gtr.co.uk/forum/upload/showt ... hp?t=45950

[oilman]

Seems my ramblings are oft quoted!

I would not use a 10w-60 unless the oil temps are truly excessive.

Cheers
Simon

[MCB]

Have a meeting in London on Monday - this will be a good run and will note max oil temp then post back, would appreciate your thoughts Oilman. And obviously thanks for the info to date, I did not realise you wrote the article I mentioned - interesting read.

[oilman]

Please let me know oil temps and I will do some viscosity calculations at those temps which will tell us whether it is to viscous at high temps or not.

Cheers
Simon

[Tomasz]

I'm using Castrol TWS (used it also in my previous cars - Subaru STI, Audi S3), which in fact is a successor of Castrol RS, and I had to admit that I'm very content with it.
Think it's suitable especially for remapped engines (higher temperatures) and for engines which are working in traffic jams during the summer temps.
So, I can recommend Castrol RWS also for your engine.
Greetings,
Tomasz