In my FJ, I use Mobil Delvac Synthetic Gear Oil 75W-90. This is a commercial gear lube engineered to meet the extended warranty and drain requirements of HD trucks Mobil Delvac Synthetic Gear Oil 75W-90, 80W-140 I buy it in 20 litre pails. On a per litre basis, far cheaper than individual litre bottles of M1 gear oil, or RP gear oil
Sure I would agree that Amsoil has some dealers that will make claims that they would not approve of. They have thousands of dealers, it's hard to police all of them. With that said without mentioning any oil companies name I will say one of them has had top ten corporate earnings off all time. Do you usually do that by being fair and playing nice? Just go to wikipedia (I know not always the most accurate) research all the big name oil companies. How much of the profits have been donated to environmental research (or not). Then try to imagine if they put the consumer and the environment first and deep pockets second how that would impact the environment if they were to market and sell oils with intervals like Amsoil. More oil changes more money, more waste.