I can tell you this much -- if your car is using a bit of oil it will DRINK synthetic! I tried a synthetic blend once. My guides are a bit worn, and the valve seals probably need to be replaced (I think the builder used the cheap hard seals), so it uses some oil. Not too much, about a quart every 2K miles, a little more if I run it hard -- basically a quart between changes, and it's about a quart low when time to change again (if 3K intervals... I've been changing at 5K). So that's not unreasonable. I put the blend in and it sucked a quart in about 800 miles! Topped off with regular oil and got a little better for the next quart (qbout 1K miles), then after topping off again it was only a quart low when I hit 3K+ miles and changed the crap out! No more synthetic until I rebuild the head AGAIN! The guides were supposedly "good", but either the guy didn't check or they were on the big side of specs. I'm planning on getting a 91-96 4.0L head from a salvage yard and rebuilding it , replacing the 88 4.0L head. ----------------------- Date: Tue, 18 Mar 2008 13:14:06 -0700 (PDT) From: Tom Jennings <tomj@xxxxxxx> Rumor has it, if you switch to synth after many miles on non-synth, it loosens all sorts of crud and makes your engine leak. I'm not testing this theory. Let us know how it works out :-) I'd run synth oil in my old motors if I thought it would not cause problems. -- Frank Swygert Publisher, "American Motors Cars" Magazine (AMC) For all AMC enthusiasts http://farna.home.att.net/AMC.html (free download available!) _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://splatter.wps.com/cgi-bin/mailman/listinfo/amc-list