Originally Posted by 05silvertacoma
i'M very HAPPY WITH THE AMSOIL Extended Life and had oil anaylsis done after my 1st & 2nd changes after switching. Everything was fine so I xtended the change intervals to 10 and than 15k.
Nice to see someone using science and engineering (oil analysis, vs. hearsay) to analyze how oil actually works. My buddy with a massive-mileage turbodiesel GMC pickup won't use anything but Amsoil.
To OP, not terribly differently from what others mention: oil threads never change much. You should see what the 911 Turbo guys, and motorcycle guys, say about all this. Often it de-volves into shouting matches fairly quickly. Actually analyzing the used oil, and publishing the results, hardly seems to slow down the naysayers.
The story's been basically the same since I started driving in the late 1980s. Mobil 1 appeared at some point after that, I used it in three race motorcycles, two BMW cars, one 911 Turbo, and eleven street bikes. Oh, and one really enjoyable 2007 Tacoma X-Runner that as of this morning has a bit over 93K miles and a brand new TRD supercharger. Bought brand new November 2006.
Not one of the above vehicles, at any time or under any conditions, ever suffered demonstrable engine, transmission wear that could be definitely pinned on bad oil. Note the world "demonstrable." My test conditions are normal use, and do not involve control groups, thus the previous is strictly my opinion and observation.
I've shifted through various synthetic oils on my X-Runner, since post first service (break-in). I have a 52 page PDF file that is the entirety of my records, oil changes and otherwise. Looking through my own records, I see Castrol Syntec (several changes), Mobil 1, Amsoil, Union 76 synthetic, Penzoil synthetic. Something must be going right for me, the truck hasn't exploded yet.
Only several times have I noticed a change in the vehicle's behavior using different "flavors" of synthetic, in all the above-mentioned vehicles, mostly warm climates:
1. A synthetic blend, back in the early days (c. 1988) kept an air cooled motorcycle demonstrably cooler, and the transmission subjectively shifted better (1983 Suzuki GS750E). I became a believer shortly thereafter.
2. 911 Turbo seems to like Motul 8100 X-cess 5W40 "better" than Mobil 1 0W-40. Turbo seals leak a bit less on the slightly-heavier oil, based on consistent usage across several tens of thousands of miles.