I just switched to synthetic oil (10W30 Wally World stuff of supposed Quaker State manufacture)on my new-to-me '96 965 (105,000 mi, but I don't know if the P.O. had used synthetic earlier)and was wondering about change intervals.

I'd planned to change it the first time at 5000mi just because I know there was some residual dino oil in there when I drained it (It took 6.5 qts to go to the full line w/ a new filter). The "old" oil was dino from the dealer with only about 1500mi on it, and it looked pretty clean, as does the head looking down through the oil fill port. Light transparent amber color on the aluminum with no sludgy stuff seen or smelled under the cam cover.

From now on, I was planning to change at 7500mi since most of my driving is 10mi or farther surburban driving (not interstate, but not close to stop-and-go city driving either).

A good friend and BMW specialist shop owner just became an Amsoil dealer and is very "high' on the Kool Aid they are serving, and swears that Amsoil is good for 35,000 mi if you chqange the filter every 7000mi, which to me seems way too high (since the filter won't remove non-particulate contamination such as combustion-produced acids and such. I also understand that the additive package (anti-oxidants, acid buffers, detergent components, viscosity improvers, etc., have a finate life, and 35,000 mi is a LONG time (700 hours of engine operation even an an average 50mph which even long distance truckers cannot maintain).

Volvo suggests 5000mi severe duty/10,000mi highway duty for oil changes with dino oil, which even seems optimistic to me. On my previous vehicles, I used 5000mi under virtually all conditions.*

He also swears from Amsoil that Mobil 1 and Quaker State use used, recycled dinosaur oil as a base from which to produce their synthetic oils (chemically altered to produce the altered molecular structure), and that Amsoil does not use petroleum base oils to make their product (though he didn't know what they do use). Obviously, synthetic oil is a formulated hydro carbon custom made or modified to produce molecular chain length of optimum length and composition to resist oxidation or coking at high temperatures with an additive package.
He's willing to sell me the Amsoil at his price (just under $50 for 12 quarts), which is only $14 more than WalMart synthetic.

1) What is everyone's consensus regarding oil/filter change intervals with synthetic?
2) IS Amsoil really so good that it can be used with extended change intervals?
3) I'm using 10W30 synthetic since I live in a moderate climate (20-45 deg F winter/50-95 deg F summer), but my friend swears that 0W30 is fine even for summer use and MUCH better even at 20 deg F. What do you all think of the need for 0W30 for summer and high speed use?

Thanks,
Bob
*A caveat to this is a friend who bought a brand new BMW X-5 SUV last year. He asked the dealer to change the oil (the original that came in the car from the factory) at 7500mi at my suggestion. The dealer refused to do so and went so far as to tell him that if he changed the oil prior to the Service Indicator lights in the instrument cluster calling for it (the Service Indicator Lights use electronic inputs to determine the engine oil life based on the actual use the engine sees) and they (BMW) could determine he'd done it, they would void his new-car warranty.

He obeyed and at almost 16,000mi his lights called for an oil change and the dealer changed the oil at that point (non-synthetic). It sure seemed to me that a brand new engine produces more metal debris (though less blow-by contamination) than one that has been broken in, and that to leave the break-in oil in for 16,000mi constituted abuse. Have things really changed so much in the last few years that this is acceptable practice?