I know this is a 1st Gen forum, but you guys seem to know about all the trucks. My friend in Utah called last night and his 01 is grinding between 3rd and 4th. He just had it serviced before a trip to Nevada last week. He had synthetic and overfilled a quart at time of service. Then it started the grind.Any ideas?

 

This kinda belongs in the 2nd gen section, but I'll give it a whirl.

What trans does your friend have? 6 or 5 speed? They require different oils. The 5 speed takes more like a gear oil and the 6 speed takes, I believe the factory fill was pennziol syncomax.

 

My uncle had a 98 and had the trans (6 speed) serviced while on a trip towing his 38' camper and they didn't use the factory recommended fluid and 700 mi later he needed a new trans. I don't know if that is going to be relevant to your friends situation but I figured I would throw it out there. If you didn't I would post this in the 2nd gen forum also is it a 5 or 6 speed.

 

The NV transmissions, Chevy and Dodge, you can ONLY get the fluid from the dealer and its (hold on to yer hat) almost 20 dollars per quart! In the NV's, I asked around, they dont need the one quart over fill either.

The factory stuff is Synthetic, it is a form of 80-90, but not. Smells nothing like gear lube. I dont know of all the aftermarket manufacturers like Amsoil, but only a select few do have a factory replacement fluid.