What would the oil capacity be for my 56 Fairlane diff,  I assume its 80 -90 oil ? Could 80 - 140 be used for my warmer climate.?



"Came too close to dying to stop living now!"

My '55 Merc manual says SAE 90 for summer and winter above -10F, SAE 80 below -10. Capacity is 3 1/2 pints or pounds, maybe the same for your Ford. You can just fill it until it begins to seep out of the filler hole and you're good. I think I'd stick with what Henry said re: viscosity.

Shouldn’t make a difference but which style rear end do you have?  You have your choice of the Ford dropout (third member style) or the Dana 44 (cover on the back).  I use the 85W-140 in the 9” that’s in my ’55 Customline but this sees Texas heat much of the time.

Lorena, Texas (South of Waco)

Its the original diff, [third member style] , just needed to know how much to buy , guess to be safe I'll grab 4 litres.  I wouldn't see temps here much below 60 F if I take the Fairlane out , and it goes upward of 100F here. So I thought the 85 - 140 would be an option, also I have a little backlash so maybe the "heavier" oil might help cushion a bit ....?



"Came too close to dying to stop living now!"

I just looked at my ’55 Ford owners’ manual and it states 3½ pints for the car rear and 3 pints for the station wagon rear.  As all ’55 Ford station wagons I have dealt with had the Dana rear, then that should be the difference in rear end oil capacities.

Lorena, Texas (South of Waco)