1984 720 MH tire question

[ztome]

I just bought chevron delo 400 sde 15w40 oil for the engine and am having trouble finding gear oil for the transmission. I literally have been to every auto parts store and none of them have strictly gl-4 80w-90. They all have dual rated oils and the closest I could find was napa's sta lube gl-4, but only in 85w-90. Any recommendations? 

 

This is all I could find online: https://www.amazon.com/gp/product/B01MZIHGH3/ref=ox_sc_act_title_1?smid=ATVPDKIKX0DER&psc=1

Is there really only one manufacturer of oil for these trucks?

[datzenmike]

GL-4 85w90 is fine

 

 Note that synthetics can more easily weep out past old seals. If your tail stock starts looking wet you will have to chance the $5 seal. Not a hard job, pull the driveshaft, pry out to old one, put a chunk of 2X4 over the new one and hammer in. Put a suitably sized socket on and carefully drive it in fully. 

 

https://www.amazon.com/gp/product/B01MZIHGH3/ref=ox_sc_act_title_1?smid=ATVPDKIKX0DER&psc=1

For this amount, get the GM Delco Friction Modified Synchromesh Transmission Oil. It's what I use and $10 -$12.

 

[ztome]

6 minutes ago, datzenmike said:

GL-4 85w90 is fine

 

 Note that synthetics can more easily weep out past old seals. If your tail stock starts looking wet you will have to chance the $5 seal. Not a hard job, pull the driveshaft, pry out to old one, put a chunk of 2X4 over the new one and hammer in. Put a suitably sized socket on and carefully drive it in fully. 

 

https://www.amazon.com/gp/product/B01MZIHGH3/ref=ox_sc_act_title_1?smid=ATVPDKIKX0DER&psc=1

For this amount, get the GM Delco Friction Modified Synchromesh Transmission Oil. It's what I use and $10 -$12.

 

Awesome. 2 quarts?

[datzenmike]

2 liters but US qts. are close enough. Change every 3-5 years or 30K miles.

[ztome]

5 hours ago, datzenmike said:

2 liters but US qts. are close enough. Change every 3-5 years or 30K miles.

Thank you