Thats interesting Whipper, because I have heard more bad than good on Amsoil.
From my research on the various boards, this is what I have learned, YMMV:
Amsoil - Alot of folks run it without problems, but when you hear about it from the well respected engine builders, most of them have seen issues with blueing of the internals and short hour to rebuild times. I have heard the term "gritty" used to describe the condition of the internals when being torn down.
Merc Oils - Havent heard anything bad about it that I can unearth. Recommended by some engine builders for certain applications
Penz Full Synth - I have heard of one respectable engine builder that doesnt like it. Most everybody else does that uses it, and other engine builders speak highly of it.
Klotz - Have heard good and bad in equal amounts. It is the oil I previously used, so the only one I can directly comment on. When my engine was torn down this year for a rebuild, it was dirty (sooty) inside. This is directly related to the ash content of the oil. So, you could say that Klotz doesnt burn as clean as some others. When my injectors were sent to Brucato to clean, I called them to get the results and they knew before I told them that I ran Klotz oil. When I asked how they knew, they said that when they clean injectors that have run Klotz that they extrude a red spaghetti like substance, which makes the injectors a bear to clean. No other oils do that. That may have something to do with my cleaning bill quadrupling because I had to replace 2 injectors that wouldnt come in. Just my experience with Klotz.
Alisyn - Never heard a bad comment about it
Not trying to start any arguements or flame wars over which oil is best. I personally believe that with the exception of Amsoil, all the major brands are just about equal for a lake use engine.
Personally I am switching to Penzoil.