Slightly overfilled 5MT trans oil. A bad bad thing?

So it was shifting poorly, so I checked the level and the stick was dry. I added 75W90 about a cup at a time, and checked the level each time. Or so I thought.... Hard to read the stick when the oil is so clean. Ended up putting in about 3 cups, or about 3/4 quart. Then I checked it, and level is about 1/4" above the top 'F' hole.

 

How bad is this? Should I pull out some oil or not worry about it?

Nothing to worry about... Can you imagine how many cars would be damaged a time after leaving their quick service maintenance garages if it was a problem?

Btw keep checking the level every time you get gas. Leaks don't plug themselves. It just might lower the fluid level by itself eventually.

The manual transmission in Legacy's depend on the gears slinging oil to lubricate the transmission so a little extra gear oil will not hurt anything. As long as you do not completely submerge the gears (which you did not) you'll be fine.

At what point would it be too much? 1/2" over the F? More?

What happens if you submerge the gears?

Mine is overfilled by about 1/2" according to the dip stick, and a have somewhat of a leak. Is this expected or has a seal gone out somewhere?

IIRC, the system can vent. How long have you had the leak? If it's been awhile, it's most likely a leak.

The transmission should "use" NO OIL AT ALL. It is not like the engine. The case (like all transmission does have a vent. If the level is going down there is a leak.

Rao - Just curious: Have you ever seen a VERY small leak from the vent? I've never seen it in my far fewer experiences, and haven't heard of it on here either. I just understand that the vent is there and that an overfill could potentially pour out of it.

Unless you really overfilled it (or used the wrong type of oil ) that isn't going to happen; or if you are a real rally racer and put the car on its roof

So worst case it seems to me is you might leak some oil out of the vent. I have no idea where the vent is, hopefully not over anything important.

You are not going to leak oil out of the vent. The vent is located on the top of the transmission.

Pretty logical place to put it

 

So why would submerging the gears be bad? The oil should still be moving around enough, I would think. Perhaps oil flying off the gears circulates and cools better. I dunno...

I'll paraphrase what I've read elsewhere. As the gears are more submerged, more energy is lost in churning the gears through the lube. This results in a bit of lost power, but mainly it generates extra heat in the oil. Which then lessens it's effectiveness as a lubricant that was designed to operate at an ideal temp.

 

Hence, there's an ideal level where energy is kept in the gears (instead of transferred into the oil) while also maximizing lubrication.

So if I have a slow leak, even if it is overfilled, I have an issue somewhere with how the tranny was buttoned back up after the clutch install, correct?

You have leak. That does not mean that the clutch job caused the leak.

Alright. Thanks rao.