first gen toyota tacoma manual transmission losses.
 

I have not driven my truck enough to find out what's going on for sure but so far its looking like its transmission losses are 2-3 times higher than my 1996 S-10 with the nv3500 transmission, judging by how hot it gets and how quickly. I did remove the rear end differential gear oil and i replaced it with used, VW synthetic transmission gear oil from a friend's 2004 era car when he had me change it for new oil, for pretty much no reason. I tend to believe it did make a difference, the rear diff runs cooler. Didn't take any measurements however. Long term most people would be concerned about lowering the viscosity but its an underpowered truck with an engine that isn't developing what it should be in my opinion. Also i'm never going to be loading the rear end with any real weight so i'm not worried about the rear axle bearings.

anyone here have a first gen? I have the 2.7L 1996 era 3RZ-FE with 300K miles on it.

I'm not interested in throwing any more money into it, but depending on how things go long term, i may put a 1.9L TDI engine in it just for fun.

There's a 2003 in my driveway, and my neighbor has a 1998. Both 4WD, 5-speed, and 3.4L V6. Thirsty trucks, but not driven much. Definitely not underpowered with the V6!