Nissan Repair: Oil Leak, nissan sentra, oil leak

Question
I have an automatic 1995 nissan sentra with an oil leak. I have replaced the oil pan but it is still smoking every time I drive it.The mechanic now says I need to replace the valve or ring where the transmission meets the engine and will need to have the transmission dropped.Please let me know if this is a possibility or are they taking advantage of me.

Thanks for your help!

Answer
Linda,

The rear main seal is what the mechanic is talking about.  Yes, you have to have the transmission removed to get to this seal.  The nice part is that is a one piece seal so the crank does not have to be disturbed or the rear main cap.  Yes, it is expensive and a pain but that is what is required to replace the rear main seal.