Where do you check and fill the automatic transmission fluid on a 1993 BMW 318is?

There is an oil-filling plug on the undercarriage of your car. However, the automatic gearbox on your 1993 BMW 318is is a sealed system and does not require user maintenance. Instead of a dipstick, the 318is uses an electronic monitor to measure and maintain the proper fluid level internally. Therefore, you should only check and fill the automatic transmission fluid if you think there might be a leak. If the fluid level is too low, it could indicate a leak or other internal problem. In that case, you should take your car to a qualified mechanic for diagnosis and repair.