Oil Change for Manual Transmission and Differentials
 

Unless I totally missed it the manual doesn't show a quantity of oil needed for the differentials, transfer case, and manual transmission when changing the oil, only to use a GL-5 90W.

Anybody done this service and could enlighten me how much oil I need to be buying? I have a '78 GMC K15.

Re: Oil Change for Manual Transmission and Differentials
 

2 qts for diff & 2qts for np205 t-case. im not sure on trans.

Re: Oil Change for Manual Transmission and Differentials
 

The '78 Owner's Manual says 4 qts for the SM465 and between 1.5 and 2 qts for the various 3 speeds.

Re: Oil Change for Manual Transmission and Differentials
 

The 465 will take a gallon, the 205 will take 2+ quarts, the rear diff, complete drain and refill 2+. All of these you fill to the bottom of the fill hole. Pickup 2 gallons and 2 quarts unless it's cheaper to buy 3 gal.

Re: Oil Change for Manual Transmission and Differentials
 

SM 465 takes 1 gallon of 80-90. I would check for leaks before you change the transmission oil. You might have leaks at the PTO covers and need new gaskets, so an empty trans is the time to replace them.