Due to an ongoing slow leak, my trans fluid is a bit low. I've got the seal to do it (once I find it again...) but I was wondering:

I've got Swepco gear oil in there now. It's still a nice color, but I have no idea when it was changed last. I've not found any good sources on Swepco locally.

So, since the color is good, I assume that I can still just top it off. Is there any issue in mixing other gear oil with this? I wouldn't think so, but...

Is there a clue on when to change gear oil? Should it be done a nice regular basis or when it appears to need changing?

I to have trouble getting swepco. I run redline MTL in mine. Used it for years in my other cars.

Swepco can be ordered from a number of places, including Pelican.

I was once very thoroughly chewed out by a professional Porsche wrench for putting Redline MTL in my 914 transmission. He recommended Swepco only. I listened to him because he was at that point rebuilding my very badly worn transmission.

--DD

The Haynes 914 manual indicates the tranny oil should be changed every 12,000 miles and the magnetic drain plug cleaned as well.

Okay, how many people do this?

Was looking for my Haynes last night, both of them seem to have disappeared, along with the FSM for the Impala and the other Haynes for the Impala and Monte Carlo...

I knew there had to be a recommended limit, but wasn't sure if Swepco had a separate mileage rate that was recommended. (1 year / 12k mi / when purple or some such).

One of my concerns with leaking fluids is that if they can get out, what can get in? Like I said, it visually doesn't appear to be contaminated, but don't mind draining and refilling it if it appears to be necessary.

But, if that's not necessary (due to visual inspection only) and I can just top it off, there shouldn't be any issues with adding in what's available (since I wouldn't need an entire $50 gallon), correct?

I've looked on the Swepco site and do not see anything (yet) that indicates a life for the fluid, other than it disappears at 50-75% of the rate of "normal" gear oil.

The transmission supposedly takes 2.6 quarts, so a gallon of Swepco is good for about 1.5 refills. Or two gallons are good for three changes.

Where is the Evil-one from Evilwerks? Mike, if you're out there, what have you learned about oil change interval and recommended oil types?

I would think that fluids leak out from either gravity or pressure, and unless your transmission is immersed in fluid (other than atmospheric air) it won't see a higher pressure outside the case, so inward leakage should not be a problem. Is the vent on top of the case large enough to allow particles to enter?