Okay, I think I have to be one of the biggest idiots in the world. I accidentally drained my transmission fluid (thinking it was my oil since it came out dark brown) and then filled my oil to twice the capacity. Fortunately the transmission is okay, but now I think I may have messed up some seals. I don’t know much about cars but my engine is now leaking a small amount of oil. My main question is what are some of the problems I may be looking at for overfilling a 2000 V6 Nissan Xterra. (I don’t want to be completely clueless when I take the car in for a mechanic to look at). Also how much do you think fixing something like this may cost?

Anyone know any good Houston area mechanics.

Thanks,
The "stupid idiot"

First, I assume you drained off the excess oil. Now since it is only a small leak, I would put cardboard on the garage floor and wait and see. Maybe it leaked out the dip stick tube or somewhere else up high enough that with the normal level it won't leak anymore after the residual drips off. So, basically unless it is making horrible noises or leaking like a seive, I would wait and see for now and not go to a mechanic yet. Oh and do refill the tranny (maybe change the filter/screen while it is empty). And do check the oil level frequently until this is resolved.

TallPaul,

Thanks for the reply. Unfortunately, it looks like it is a persistent oil leak (though only a few drips a day). Anyway, do you know the names of the different seals where leaks may be coming from (i.e. rear main seal etc) Also how much would something like a rear main seal cost to replace? Thanks.

Is the leak from the engine or transmission? I'd give it some time, and keep on with TallPaul's idea. If you end up with a leak, it was probably going to leak soon, anyhow. You do need to give the oil or transmission fluid time to drain off your Xterra before you worry about a leak.

One other idea. There is a product Auto Rx (http://www.auto-rx.com). It is an ester engine cleaner that also conditions seals. I had a power steering leak at the shaft input to the rack and put in 1.5 oz AutoRx. The leak went away within 500 miles or so. For engines the dosage is larger, about 2 oz per quart. Since it also is an engine cleaner you must follow the instructions closely. I ran it in my pickup truck at 110,000 miles. I did not have leaks, but wanted to clean the engine. Though many at Bobistheoilguy.com swear by it, I am not convinced as my pickup still seems as dirty as before, but as in my power steering, it did help. Seems no harm trying before going into seal relacement.

This is just to make you feel less like an idiot bmtxlaw, but when Saturns first came out in '91 with their drain plug and spin on filter transmissions, most people removed the wrong filter to so an oil change, as the oil filter was located in the back of the engine, and the tranny filter was located in the front.

You can imagine most people's reaction to removing this filter and seeing dark red come out, instead of dark brown fluid (meaning used oil).

Even given this slight little issue, I think the worst mistake they ever made was dropping this transmission and going back to a conventional pan transmission. I know why though, because the transmission was "bullit proof", as long as you changed the fluid/filter once a year, the tranny lasted neck and neck with the 1.9L 4 banger engine that they used.