Fluid in a 5 speed '90 Chevy k1500

[Jorge6.5]

What is the best or recommended fluid for a half ton 1990 Chevy truck? How much fluid is needed? Im not sure if it is a nv3500 or nv4500. Maybe someone can fill me in on which one I have. It's a V8 gasser.

Thanks

 

[tanman_2006]

You will have to find out. You could also have a getrag too i bet. They all 3 take different oil.

 

[THEFERMANATOR]

From what I could find you should have a GETRAG 5LM60 and it uses SYNCROMESH fluid.

 

[jrsavoie]

i WENT 800,000 miles on the Getrag in my 1989 C2500 with Amsoil heavy duty gear oil

I liked that transmission far better than the NV4500 in my K3500. The shifting spots were better and it shifted smooth. I've heard bad things about them holding up, But all I ever did was change the oil in mine.
The truck weighed 8900 lbs. minimum about 600,000 of those 800,000 miles

 

[Jorge6.5]

i WENT 800,000 miles on the Getrag in my 1989 C2500 with Amsoil heavy duty gear oil

I liked that transmission far better than the NV4500 in my K3500. The shifting spots were better and it shifted smooth. I've heard bad things about them holding up, But all I ever did was change the oil in mine.
The truck weighed 8900 lbs. minimum about 600,000 of those 800,000 miles

Very awesome! You used synthetic gear oil or the synchromesh from amsoil?

 

[jrsavoie]

Synthetic gear oil. It was what was recommended in the early 90's when I switched everything to Amsoil. 75W-90

 

[THEFERMANATOR]

Synthetic gear oil. It was what was recommended in the early 90's when I switched everything to Amsoil. 75W-90

The GETRAG is very similar to the NV3500, and as far as I know GM has always used ATF or syncromesh in these transmissions. Syncromesh is a 5W30 synthetic fluid VS the 75W90 fluid. They use it over the thicker gear oil for better cold shifting, and increased oiling when cold or in cold climates.

 

[jrsavoie]

The GETRAG is very similar to the NV3500, and as far as I know GM has always used ATF or syncromesh in these transmissions. Syncromesh is a 5W30 synthetic fluid VS the 75W90 fluid. They use it over the thicker gear oil for better cold shifting, and increased oiling when cold or in cold climates.

I had good luck with the gear oil. Maybe it was just luck. I almost always call Amsoil tech to ask about application info. I know I did way back then. Never had any cold shifting issues or rear end issues - same oil in both. That's a lot to ask for those kind of miles and that kind of constant load.

I had to drive it clutchless a few times, for a week at a time. The clutch went out while I was on the road and I had to wait til the weekend to fix it

 

[Jorge6.5]

Very interesting. That's great that you had good luck with the gear oil.

I think I'm gonna try for the synchromesh cause that's what they recommend now a days on the amsoil site

 

[tanman_2006]

I think the key to the gear oil working is the fact that it was that it was synthetic and flowed easier when cold.

 

[jrsavoie]

I think the key to the gear oil working is the fact that it was that it was synthetic and flowed easier when cold.

If it wasn't for this thread and I got another, I would have just used the gear oil and never know it wasn't spec anymore. If I got another 800,000 miles on a tranny, I wouldn't care

 

[THEFERMANATOR]

Very interesting. That's great that you had good luck with the gear oil.

I think I'm gonna try for the synchromesh cause that's what they recommend now a days on the amsoil site

I run the AMSOIL syncromesh in my transfer case and have had good luck with it.

 

[GM Guy]

I run royal purple synchromax in my 5LM60 in my 91 v-6 5spd 2wd. tough tranny, have towed with it and abused it at college.