Finally got around to doing my oil/tranny fluids and noticed that the entire bottom half of my transmission case is coated in oil. The oil that came out of the transmission when I opened the drain plug was clear and thin (much thinner than I recall, in fact looks almost like motor oil). I have no idea how much came out of the transmission, but it took less than 45 seconds to drain.

Any idea what could be going on here? The car is tracked and autocrossed regularly, so it does get its share of abuse.

 

MTF is about the same as 10w30 for looks. The trany hold 1/5 of what the engine holds, so 45 sec to drain is about right. I did not time it the last time I changed it, but it was fast. It you leak oil from your filter (too tight, ot not tight enough) it will end up on your oil pan and then the underside of the trany.don't ask me how I know that.

 

The oil filter was on way too tight. I had to crush it just to get enough torque on it to get it off. Perhaps that's what happened.

 

Any oil leak from the engine (be it from the valve cover, oil filter, oil pan gasket, oil plug, rear main seal, head) will find its way to the underside of the engine/tranny.

 

If you overfilled the trans, it can blow excess fluid out of the vent on top of the trans. Was the fluid below the fill plug on level ground?

 

Yes

 

if there is a doubt where the leak is coming from, they make UV leak check dye to add to the oil. You can track the leak down with a black light.

A cheap alternative is Tinactin aerasol foot powder, clean the area and spray away. Then look for the wet spot.

 

Sorry, I misread your question. All of the oil was below the fill plug

Actually, I think I had the car tilted with the driver's side up last time I did the transmission fluid. So, it was probably overfilled by 1/3 of a quart.

 

Overfill may have caused it. I'd recheck the fluid with the car level on jackstands, and give it a good cleaning. Non-chlorinated brake cleaner doesn wonders cleaning up oil leaks.

 

I had a similar incident due to the fill plug loosening - possibly due to vibration. The bolt was still in, but was a turn loose and a small amount had siphoned out over a 1000 mile period. I've also heard of leaks due to cracked or malformed washers (due to excessive over tightening or the washer being used multiple times).