I just purchased a 1991 Nissan Pathfinder, I needed to change my oil but I can not find the drain plug. I thought I found it near the driverside of the car just behind the front tire but when I took the plug out just transmission fluid came out (but I didn't know it was transmission fluid at the time). I do not see any other plugs under the car. When I drained it the fluid was black like bad oil so I put new oil in. I then realized that it wasn't the oil I drained and now I can't take out the extra oil I put in. There is about three extra quarts and my car is smoking a lot. Know where to look for it?