Date: Thu, 13 Feb 2003 13:50:09 +0000 From: Grunff <grunffnopsam.com> Subject: Re: use fossil or synthetic oil?
Paul Halliday wrote: > On older cars where the oil > used by previous owners is not known, there is a risk that synthetic oil > will clean away mineral deposits and slight leaks may occur, but I've been > lucky. "Slight risk"? "Slight leaks"?? Paul, I suggest you've been *very* lucky. While I'm in no way disputing the fact that synth is very good, and especially appropriate to turbos, there is a real, big danger of *major* oil leaks when switching from mineral to synth at higher mileages. I've personally experienced this twice, and seen it happen to others many times. I think the main mechanism is seal shrinkage (mineral oil swells seals quite a lot, which compensates for seal wear, whereas synth doesn't). Unless you're happy to change your front and rear crank seals, and probably your oil pump o ring, then don't change from mineral to synth at high mileage. This doesn't apply to the OP - carry on using synth. -- Grunff