Probably the most raced and modified modern chassis BMW, the E36
is a fantastic base for a world class performance car.
For both US Spec and Euro Spec E36 engines, one area of concern, but that is often overlooked is the oiling system...
Very common failure Number 1) The oil pump sprocket (drive gear) retaining nut backs off it's drive shaft, and the gear proceeds work it's way off causing the oil pump to stop, and lose oil flow & pressure.
Common failure Number 2) The gear physically shears off the oil-pump shaft, due to the weak OEM spline (this happens with the sprocket and nut still attached!!!)
In both of these cases, your engine is gone; usually suffering spun rod bearings, scored crank, and possibly worse depending on how stressed and at what RPM the engine failed.
To be clear:
This oil pump failure can effect 100% stock or modified E36 6 cyl engines.
A common, but misleading internet fix is either to weld the nut to the shaft or to safety wire through the shaft as a nut-stop.
This only tries to stop problem #1 and does not address problem #2 and in the case of welding, eliminates serviceability of the oil pump.
VAC engineered what has proven to be the best solution on the planet that addresses both issues with our popular Oil Pump Upgrade Kit (OPUK for short). This is made available for most popular BMW engines and can also ship as a newly rebuilt oil pump with the upgrade already installed.
-----While the US spec versions of the S50 were not as potent as their euro brethren, they trade off power for simplicity and reliability, and with some tuning can be equality as fast.
Here on the US spec engine, the next area that requires attention is the oil pan itself.
Euro spec S50B30 and S50B32 engines have a dual pickup similar to that in the S54 engine, this pickup greatly improves the ability of the engine to stay lubricated as it has two feed locations for the oil pump. The US spec S50/52 and M50/52 are not so equipped and therefore require a solution if the car is going to see high lateral loads, like those on the track, or of a highly tuned street vehicle.
Enter the Oil Pan Baffle.
A simple looking device that helps trap oil against the point in the oil pan where the single pickup is located. This device is contoured and engineered beyond its outward appearance and is in fact a crucial upgrade for those who enjoy driving there M3 hard.
Performing the two upgrades above will ensure that your M50/S50 has the highest rate of survival against performance driving related oiling system failures.
As for oil, VAC recommends a high quality full synthetic such as Valvoline Racing, Total (Elf), Motul, and Castrol. In the engine we prefer these brands over Redline, Mobile 1 and other products from our engine buiding experence.
More and more we have seen local customers come in with engine failure due to oil starvation on street driven non-tracked cars , reinforcing the doctrine that all E30 M3 owners should have an Oil Pan Baffle.
There are varying opinions and theory's on what works best for just about everything on the E30 M3, especially when it comes to lubrication.
There is only one way to know what really works; many years of experience with everything from daily driven beaters, to all out race vehicles.
"What weight oil should I use in my S14, what fluid for my transmission, what is best in the rear deferential"?
These are common questions of the E30 M3 owner looking for the best match for his or her car.
Technology has changed in the 20 years since the E30 M3 was new and so has the science of Tribology (study of friction & lubricants, ect).
When new, BMW specified 15W-50 weight mineral oil in the S14. However, running a 15W-50 weight synthetic oil, or a thinner synthetic like a 10W-40 provides the same or better protection as the 15W-50 weight mineral oil in all cases, with none of the drawbacks.
Thinner oil flows easier, faster, and carries heat away from surfaces quicker with less work required from the oil pump, and less resistance on the crank. Thinner, high quality synthetic oil also flows better in the cooler weather along with equal too or better film strength than mineral oil of a higher viscosity meaning longer life of all lubricated components. Top quality synthetic lubricants enjoy longer service life in lubricated components meaning they need to be flushed and replaced less often, this equals more convenience and a better value.
Using a high quality synthetic ATF oil in the transmission of your E30 M3 also provides the same benefits as above as well as the smoothest all weather shifting.
Cold or hot, the E30 M3s transmission is less smooth than even your average BMW, but should go into all gears on the first try. If your car does not, and your shifter assembly is in proper order (bushings, circlips, linkage is tight, selector rod is not worn), chances are your transmission fluid is not a good match for the synchronizers in the transmission.
Redline MTL: some people have good luck with it, some do not. Many times it is better than what is already in the car and provides a dramatic improvement, however synthetic ATF has show to provide the smoothest shifting across a broad temperature range and is the preferred choice of VAC in the Getrag 265.
For the differential, again, choose a quality lubricant, synthetic if available, that is specified for use with a LSD (Limited Slip Differential).
If you track your E30 M3, the high-slip nature of the OEM LSD generates much heat and friction, invest in a quality lubricant and finned differential cover, change this fluid often.
It is important also to remember, synthetic oil does not cause leaks. If your engine has a worn, or dried up seal, or a small "weep" type leak, the finer composition of the synthetic oil can find this gap and can work its way out easier than mineral oil.