My recent experience with Amsoil
 

A few weeks ago I bought a modified D***e pickup. Yesterday, I went
over down the way to an Amsoil dealer and got some of the hypoid gear
oil and transmission gear oil products and changed out the oil in the
(probably stock) rear end and the Clark 5 speed transmission. I drove
it around a while and within a half hour, the Clark transmission was
shifting easier and running quieter. it's still loud, they all are, but
it is definitely quieter.

We'll see how this turns out. My next project is going to be to put a
Frantz oil filter and a remote full flow filter on the engine. I have
also bought a set of heads as I am going to clean up the ports on them
and then have Stellite seats and Inconel valves installed in them so I
can swap them out in a day and not have the truck down. Then I'm going
to have the bed rhinolined and when that's all done, the large propane
tank I found for $50 and am having cleaned and hydrotested will go in
there. I'm going to convert her over to straight propane. When I do
that I probably will go over to synthetic oil.