Q: I recently replaced the automatic transmission pan gasket and filter on my 1991 Toyota Corolla because of a small leak. Being the enthusiastic beginner/do-it-yourselfer, I did the work myself, and now I think something has gone wrong. After tightening the last bolt and refilling the pan with Dexron III transmission fluid to Toyo specifications (2.6 quarts), I went for a test drive.

I accelerated from a stop light, and the acceleration was poor. I heard the motor working but no power. I managed to get it moving. I pulled into a parking spot and checked the level. It was near empty. After adding a bit more fluid, I noticed better acceleration. But after driving about 10 miles, acceleration became poor, and I checked the fluid level to find it low again.

Why the low read on the dipstick? Why the poor acceleration? The only thing I can think of is the use of newspaper to clean the pan. I made sure there was no lint left behind. Maybe I was wrong? There are still minor drops on the bottom of the pan. Maybe it's just old. Any ideas? -- C.R., Westchester

A: C.R., I don’t think it has anything to do with what you used to clean the inside of the pan, as long as there was no residue or pieces of paper left. Whenever the automatic transmission fluid is replaced, you should start the engine and move the shifter through the gears. Then you should recheck the fluid level before going for a road test.

Even though the service manual specifies 2.6 quarts, always go by the reading on the dipstick. It’s also important to follow the manufacturer’s procedure carefully when checking fluid levels. According to the service information for your Corolla, the fluid level should be checked with the engine running and the transmission fluid temperature at 158 – 176 degrees Fahrenheit. It is important that the fluid level be precise, neither under filled nor overfilled. Damage to the transmission could occur in either condition.

Apparently, you still see drops of fluid on the pan and that would indicate a leak. I would recommend you bring your Corolla to a repair facility that specializes in transmission repairs and have them determine where the fluid is leaking from.

Q: Have you heard about filling the tires with Nitrogen gas over regular compressed air? What do you think? -- S.N., Evergreen Park

A: S.N., yes, I have heard about filling tires with Nitrogen gas. If it’s good enough for racecars and airplanes, it ought to be good for light-duty vehicles, too. The main benefit is that Nitrogen molecules are larger and will help maintain tire pressure longer. If motorists check the pressure of their tires frequently, or drive a vehicle equipped with a tire pressure monitoring system, Nitrogen filling is not likely to offer substantial benefits.

Until auto or tire manufacturers require Nitrogen filling, motorists will continue to have a choice of regular compressed air or pure Nitrogen. Keep in mind that the single most important aspect of prolonging tire life is to keep them inflated at the proper pressure. Wheel balance and wheel alignment also play a role in getting the most mileage out of your tires.

AutoAdviser: Ira Siegel is an Automotive Instructor and ASE Certified Master Auto Technician. If you have auto-related questions for Ira Siegel you can call and leave your questions at the Auto Adviser Hotline at 708-633-6839 or e-mail a question to Autoadvisr@aol.com.