Originally Posted By: finalyzd
Originally Posted By: nwjones18
I have a 4x4 1975 F100 that calls for straight 50w in the 4 speed trans and the transfer case. Neither Autozone nor Advance have it and they say they cannot even order it. Any ideas on where I could find some locally?
Wouldnt 20w50 work?
No, it would not work. It was specifically designed to use a straight grade oil, rather than a multigrade oil that has viscosity modifiers.