rear main oil seal on 1993 Chevrolet Lumina

where is the rear main oil seal located?

2 answers
Rear main seal is located at the rear of the engine between the engine and the flywheel or flexplate/torque converter. To replace the seal the transmission must be removed which is a big job.
On all engines the rear main seal is located at the extreme back end of the crankshaft where it passes between the oil pan and engine block. To replace it requires dropping the oil pan and loosening the crankshaft. It is usually a two-piece seal (upper and lower) split in half.