Ford 640 Differential OIl Quantity

[MGBBob80]

Hello All,

Wondering how much oil should go in the differential of my 1955 Ford Model 640. My owners manual (fairly new reprint) and factory manual say 8.5 quarts; however, I drained more than 12 quarts a little while ago. Putting 8.5 back in does not raise the level to the plug on the side of the case that is used to check the level.

Should I continue filling until I get oil of the side plug? Or should I add 8.5 and leave it at that?

For info - the transmission took exactly 6.5, which is what the owners manual and factory manual requires.

Any info is greatly appreciated.

Bob Finley

[Soundguy]

add oil to the diffy till it comes out that pipe plug hole.

utf meeting m2c134 spec or 80w90 gl4+

[MGBBob80]

That makes sense. I was just surprised at how much oil went in as compared to what the books said should be there. Thanks! Bob

[Soundguy]

it wouldn't burn up and explode a couple quarts low mind you.. but no reason to NOT fill it to the check level.

ring gear is going to 'distribute' the oil pretty well.. etc...

not much surprises me working on 60 year old equipment. find all sorts of things...

[MGBBob80]

I have 10 qts in it now and the level is about 1/2" below the check level hole. She ran fine, but I'll be happier when I get it topped up tomorrow.

[Soundguy]

without my manual in front of me i don't recall if the 8xx had a higher oil level capacity than a 6xx.. but I do know they had a heavier rear. IF htere was a capacity difference.. it might be a swapped part ( not saying there is a difference.. just wondering out loud.. with no manual to reference in front of me.. )

either way.. fill it to the check level and you will be good.