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Differential Oil Capacity


Jedi Trainee
Country flag
My factory shop manual lists the rear axle oil capacity for the Healey Mark 1 and 2 series at 3 Imperial Pints or 3.6 U.S. pints, but then lists, in parenthesis, 1.7 litres. The litre reference is contradictory to the capacity listed in pints. I didn't measure the amount of oil that came out of the differential, but I have now put two full quarts through the filler hole, and am finally getting a bit of oil backing out. I find I have now put more oil into the differential than is listed for the standard gear box with overdrive, but in this case, as well, there is a much larger number listed for litres (liters to us), 3.6 litres. I'm somehow misunderstanding the capacity listing, or what? I must say the differential is quite large and the filler hole is rather high on it, so it seems implausible that it could require as little as 3.6 U.S. pints to bring it to the proper level.


Great Pumpkin
Country flag
it seems implausible that it could require as little as 3.6 U.S. pints to bring it to the proper level.

SO; on a level surface fill the diff with the proper oil until it just starts to run out the filler plug hole and you will be good to GO!!----:wink-new:


Freshman Member
The workshop manual numbers are correct. I changed the diff fluid in my BT7 this past winter and put in a little less than 2 US quarts before it began to flow out of the filler hole. I too was confused at first by the workshop manual numbers but then realized that with 2 US pints to the US quart, 3.6 pints would be 1.8 quarts. Liters are a little larger than quarts so 1.7 litres make sense. Search "US pints to litres" and you'll get a number of conversion calculators that also confirm the numbers in the workshop manual. IMO the diff will operate fine whether it has 1.8 quarts or 2 quarts of fluid.


Jedi Trainee
Country flag
Thanks for the guidance. My assumption was exactly as Keoke says, that the diff was properly filled when the oil started to back out of the filler port with the car parked on the level. I would have benefitted from looking at Webster's Weights and Measures. A U.S. quart (two pints, not four) is 0.946 liters.


Obi Wan
Country flag
OK, now you messed up a lot of minds. Considering a qt is 32 ozs and a gallon is 128 ozs. So how is the fifth 32 ozs squeezed in?


Country flag
Oh you guys got trolled. He said "US" for quart but left out "imperial" for gallon. Though it isn't exactly 5.

And why dig up an 8 year old thread as a first post?
Last edited:


Obi Wan
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Don't know, just popped up here for to read


Staff member
Country flag
Heard a good tip from a British lifelong auto mechanic at breakfast this morning:

Before you drain oil from a component (diff, gearbox, whatever), first remove the fill plug. The reason being that if you first drain it and then find you can't remove the fill plug, you have no way to re-fill the component.

Now that's old-time mechanic wisdom if I ever heard it!
Country flag
You can also fill your diff through the end of the axle tube--just jack up one side and pour away.
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