Should I switch? Amsoil vs Mobil 1... yet again...

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Nov 24, 2003
Colorado Springs, CO
I know this has been beat to death; However, now that I have gotten over the shock and awe of my most recent UOA and the abnormal indications on viscosity and aluminum with S2K 0W30, should I return to my roots and go back to Mobil 1 or stay the course and put another round of S2K in my engine. (Not bad, all one sentence!) For those who don't remember... 2001 Tahoe, 5.3L 39,000 miles. Steady diet of M1 up to 34,000 miles. Amsoil S2k for 5000 miles so far. The issue is that I drive low miles, usually under 10 miles per trip. My stubborn side says that if the Amsoil has failed to perform in 5000 miles then Amsoil should replace it. I wrote AJ Amatuzio a letter but doubt that he will respond. All advice is welcome, I need to do something this weekend (i.e. change oil). Special thanks to TooSlick who took his own time to call and discuss my initial situation with me! Great help from the folks who use this site! Thanks, Doug in Colorado [ January 22, 2004, 02:37 PM: Message edited by: Doug C ]
I know this will sound strange coming from me (someone who has overreacted to a bad UOA and quickly switched oils), but I think you should stick with Amsoil for at least another interval or two, and then see how it goes.
Doug please don't take this wrong but some of these newer GM engines are not going to give sterling UOA's for the life of the vehicle these days . Not saying yours is a bad engine but I've seen some of these start out life A-OK then head south after 30k miles . Some after 80-k , it just depends . I would not blame the Amsoil if that engine were mine . But it's not so disregard my post if you want .
Doug, I'd say 9 tmes out of 10 it's no the oils fault. However, some oils do work better then others. If you did decide to stay with Amsoil, I'd go with their 5w/10w-30. Still give the 0w-30 a shot and see how it looks a second time around. [Smile] [ January 22, 2004, 07:02 PM: Message edited by: buster ]
OK, Thanks. All of this sounds logical. This horse is dead. Just wanted to bounce it off of you guys. Don't want to beat it any more. Doug
Doug - another suggestion: You may want to try ASL 5W-30. A whole lot cheaper and I'll bet the UOA will look good [Big Grin] I still think the Powerfoam had a negative effect (on the oil), but that's hard to prove at this point.
You engine will react the same to both products. Theres always an amsoil mobil 1 bashing thread here somewhere. Just use fully synthetic and youll be fine.
I went back and looked at the UOA. I think the additives especially Power Foam clouds the issue. In fact I don't put a lot of stock in a lot of the uoa's I see here, because many are always done in conjunction with some after-market additives and air filtration changes etc. This seems to introduce too many variables to compare oils themselves. Also, I question the method of retrieving the sample. With the way you drive, I'm not sure you'd be getting your money's worth with this Amsoil anyway.
Thanks for everything. I just got done changing the oil, filter and front differential fluid. Used S2K 0W30 for the engine and S2K 75W90 on the front diff. Figured since I was under there, might as well change the front diff. Had previously changed the rear and transmission to Amsoil fluids. I'll give it a few thousand miles and do a UOA and see what the results are. No PowerFoam this time... it doesn't need it anyway! Thanks again, Doug
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