Originally Posted By: hominid7
Many older German engine mgmt systems required very very high oil pressure numbers to keep them happy. My '89 VW Jetta (gas) only allowed 10w30 AND 10w40 up to 50*F.
In the car above, given the chart above, i'd run nothing except dino 20w50 year-round. If the temps got significantly below 0*F i'd use 10w40.
I don't think your Jetta had an oil cooler, so the thicker oils seem reasonable for hotter climates.
The engine management system on the E30 325 is 100% electronic. Oil pressure has nothing to do with it.
I have an E30 325is. Compression is even and at the top of the specified range, and the engine runs fantastic with 243k on it now. When I bought it at 220k, there was a Jiffy Lube sticker on it stating 10w-30 was used. As far as I know, 10w-30 could have been used for it's entire life before I bought it. Who knows? If it was, it certainly didn't hurt anything. I fully expect to get at least 300k out of the motor, and more likely 400k.