I found that RP was dreadful in my Toyota manual transmission it lost it's cold shift properties in about 10K miles. As far as wear metal is concerned it seemed to work just great at preventing abnormal wear but who cares about that when you have to fight to shift gears int he cold? I have not tried Amsoils lasted products so I willnot pas judgement on it. I can say this when I worked for GM I worked with a lot of Corvette nuts!!! I was one of if not the first guys to recomend 50/50 MTL/MT90 to some 10th level executives for their poor shifting Corvettes based on my experince with Toyota MR2's and notchy shifting. THis combo grossly out performed GM's syncromesh which was made at the time by Texaco. Pensoil Syncromesh is cheap and affordable but beyound that I never say where it was any better then the Synchromesh Texaco made for GM.
In the past having tried M1,Amsoil,Redline,Royal Purple Swepco,Cenpeco,Schaffer's I have come to the point that the only gear lube I will buy for any manual transmission I own is Redline products.They have time and time again proven themselfs to be better in the field then anything else I have tried. Shift feel is really important to me and so is cold weather performance. Any lube should be able to prevent abnormal wear but cold performance and shift feel is something most companies miss the bus on!
Now with that said on a transfercase or differential I am not at all brand loyal. I am only loyal to Redline with regard to what I put in a manual transmission and it is not for any other reason then what I mentioned above and that is performance.
