If your car is showing signs of transmission issues and you're a die-hard DIY auto-repair fanatic, you may want to change your mind for a bit and let the professionals take care of the transmission. It's tempting to tinker around with the transmission to see if the fix is simple enough to handle at home. However, even simple repairs can lead to big problems if you don't handle them exactly the way they should be.
Overfilling and Underfilling
For one, there's the risk you'll overfill the transmission. This is a closed system; put too much fluid in, and it can blow a seal on the transmission, resulting in both damage and a leak. Shifting gears can become unpredictable, too. If you go in the opposite direction and don't fill the transmission with enough fluid, your engine can experience oil starvation simply because there isn't enough transmission fluid or oil to fill the system properly.
Overfilling the transmission can also cause problems with the pressure release vent. The transmission fluid can expand as it heats up and start coming out of the vent, too, which is a mess because that vent is meant to release air only.
Correct Fluid Type
There's also the problem of which fluid to use. Despite the name automatic transmission fluid is actually used in some manual transmissions. Other manual transmissions use motor oil and not a specific transmission oil (though there's that option, too, for some cars). And even automatic transmissions aren't that straightforward in terms of fluid use because there are several different types of automatic transmission fluids. Your car will take one type, and if you can't find the manual for your car or you're dealing with a very old car, then finding the right fluid can be tricky.
If you have a leak in the transmission, even something as basic as finding the leak can result in damage or misdiagnosis. The fluid can discolor over time, so going by color is only partly helpful, and the leak can occur anywhere in the system. If you drive a manual transmission car that uses motor oil in the transmission, the job is even harder because now you have to check out the regular oil system to ensure there are no additional leaks there.
Sometimes saving the money isn't worth the trouble of going DIY with car repair. Instead of wasting a day, take the car into a transmission repair center like S & A Transmission and have the specialist techs there take care of the problem.