Gear oil coming out of breather

[bryant2482]

Any body know what would cause gear oil to come out of the little breather vent on top of a 5 speed trans?

[datzenmike]

Over filling. Possibly wrong oil foaming.

[bryant2482]

Yep that explains it! There was a good extra quart that I took out

[datzenmike]

The 71-B holds 2 liters or 4 1/4 US pints. Or until you can't add more to the fill hole when sitting level (more or less). Has to be GL4 NOT GL5 no matter what the collage boy behind the counter says about GL-5 being higher protection. Any Datsun transmission oil choice must be marked 'copper alloy' or 'yellow metal safe' for use. 90W will do or equivalent in synthetic although synthetic may wet the rear seal unless you put a new one in. It's very thin and slippery. I've been using the GM Delco Friction Modified Synchromesh Transmission Oil with good results. It cold shifts now without light grinding the first few times and I can now down shift without grinding which I could never do properly before. Shifts are much less effort so naturally they are faster.

[bryant2482]

Yea I put in 2 quarts of Royal purple 75w-90. It's the only one I could find locally that's good for the yellow metal

[G-Duax]

There isn't a NAPA in sin city ?

Napa sells CRC StaLube.

But the GM Synchromesh is good shit also.