Oops my mistake then.........
Even from the fill hole I was only able to get about a quart in it.
I guess if it flows out the vent cap I will have confirmed it was too much.
Although, as long as there is enough room in the case and the air can vent as the oil expands due to temp, can you really have too much lube?
It wouldn't seem bad to have too much oil in a gearbox, but you run a chance of blowing the extra out the vent and creating a big mess around the rear wheel and tire.
Not that drag is a big deal on these cars, but more oil will take more effort to turn the box and rob some power from you.
Also some boxes do not have seals that are capable of being flooded with oil and will leak. Most of these gear boxes are designed to keep in splashed oil, but not when oil covers the seals all the time.
Running the correct amount is the best in all cases.
