Wow looks like I stirred the pot on that one eh? GOOD,, Thinking and trying it out are what makes great parts. Let's see if I can remember the questions.,,, Oil stays clean according to the shape of the engine, rings and PCV system. On a good tight motor (like my 02 Poncho GP with 102 on the clock) it stays clean for several thousand miles. It's REAL dirty when it comes out but I have taken a valve cover off to inspect at 100k and it looks almost like NEW inside! Aluminum rockers still shine. I got the car as a demo with 12k on it and Mobil1 every 7500 since then. Uses about a pint between changes. I'll pull the heads soon and replace the crap OE valve guide seals with some premium ones, touch up the valve seats and put new head gaskets on it. Good for another 100k. Those 3800 GM motors are good as any better than most! Seen em go 200k+ and not been apart. Think 9k oil changes are a stretch?? I once had a diesel rabbit. Bought it with a bad engine. Rebuilt it an decided to try a test,, NEVER CHANGE THE OIL! Now those things used a bit of oil even when tight, about a quart every 1500 miles or so. I broke it in on Shell Rotella-T 15-40 (my favorite dyno oil) and then ran Mobil1. I added oil as needed and changed the filter about every 5-6k. Had over 30k on it when I sold it and the inside looked like NEW! Wished I would have kept that little 50MPG getter now!! I break in my motors with Shell Rotella-T 15-40. Couple of reasons. Just to give the rings a little time to get friendly with the cylinder walls. And since I usually run about 1500 miles or so break in I don't need to be dumping high dollar Mobil1 out so soon. I've done it this way for a long time and it's worked for me. Cold weather starting. As many of you who live up north (I'm from Cleveland originally) can vouch Syn Lube makes a HUGE difference when the temp drops below zero. Try starting your 20-50 Castrol engine when the temp is -15 or LOWER. You can hardly tell the difference with Syn Lube -15 or 104' (as it was here today). Syn lube has MUCH higher tolerance for temp. Most dyno olis are COOKED at 350', syn lube is good for at LEAST another 100' over that. Ever see an engine with dyno lube that has been SEVERELY overheated? The oil is CONGEALED in the pan to the point it WON'T come out the drain plug! Why do you think NASCAR and other racers are so big on syn lubes? MORE HP of course but also a degree of protection dyno lubes won't give when that high dollar race mill is running 230' under full throttle in traffic!! Many race teams use SUPER thin oil for qualifying (as thin as ZERO weight!) to get that last HP. I swear it looks like WATER!!! Syn lube is good as is if you have roller lifters. If you have a flat tappet or flat finger follower engine I'd be inclined to add ZDP (Zinc). You have to be careful here, to much ZDP can screw up your OXY sensor and cat convertor. But both of those are USUALLY cheaper to replace than a cam so I add ZDP to my non roller motors. I have not had a problem doing this that I'm aware of. You need to make your own choice. One place where syn lubes (or at least some of them) seem to have a problem is with antifreeze dilution. They do NOT like Ethylene Glycol ! I run GM stop leak tabs in ALL my motors as a little extra insurance against coolant seepage. So in a nutshell, I run Shell Rotella-T 15-40 for about 1500 miles break-in then switch to Mobil1 10-30 for 7500 changes and add GM stop leak tabs to the coolant. If it's a used high mileage motor or one using oil I'll try 15-50 at least during the warm months. My alternative dyno oil is Shell Rotella-T 15-40. But HEY,,, That's just ME!! Bruce Hevner -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.amc-list.com/pipermail/amc-list/attachments/20070810/b84847c3/attachment.htm _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://www.amc-list.com/mailman/listinfo/amc-list