Synthetic vs Petroleum oils

[mnichols]

I just purchased a 1995 M3 to make into a track car. It.s in the hands of a trusted mechanic who drives a Ferarri, Benz and several BMWs. We got into a discussion about engine oil, and his personal experience on changing from petroleum based oil to synthetic. On his 90s vintage cars he often developed leaks in valve cover and other gasket sealed devices shortly after switching to synthetic. Has anyone had similar problems? I'm about to change the oil in my 95 M3 for the first time, I'm not sure if the past owner used petroleum or synthetic and I'm about to use synthetic.

[saltshaker185]

the reason these leaks appear is that synthetic often cleans out your oil passages in your engine. The petroleum based oils create buildups in certain parts and as they age actually can stop up any leaks that would appear otherwards. The way i look at it use synthetic. If a leak occurs replace the gasket as there should have been a leak there anyways but you had oil gunk clogging it up.

[Linds]

^Exactly. I switched to synthetic when I got my car and the valve gaskets did start to leak, but they're really easy to replace.