Trans fluid and differential fluid

[chuckcloutier]

I have a 1981 FI with 52000 miles on it. Slowly going through everything. Any recommendations for correct/best manual transmission fluid and differential fluid?

Always appreciate the great input and advice from this forum.

Chuck

[courtenay]

Not sure about differential fluid, Chuck, but if you do a search on transmission fluid, you will find a plethora of opinions on on various transmission fluid options. I use GL - 1.

[TX82FIAT]

75W90 for the diff. Some people use synthetic as well. The GL1 is for the trans. Get a pump for both it makes the job a lot easier.

[chuckcloutier]

But the diff fluid does not have to be rated GL1, correct? Any particular weight for the trans GL1?

[TX82FIAT]

The NAPA part number is 65-201 and it's called SAE 90 Mineral Gear Oil. I think I paid about 10.99 for a gallon.

[JConnerly]

Whether you use a pump or gravity to get the oil into the tranny or diff, warm the oil in pan of hot water first. It will flow much easier. Can be very frustrating waiting for it to run through that little tube!

[GeorgeT]

Be sure to loosen the fill port plugs before draining the fluids. If you drain the fluid and then find the fill port plugs stuck, you are screwed.

[124cso]

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[chuckcloutier]

It says manual right in the original post.