How much will it cost to fix a severe oil leak in a 1991 Buick Regal?

I put several quarts of oil in the car before I left to drive 110 miles, and when I got to my destination, there was no oil left and oily residue all over the back license plate and trunk. How much will this typically cost at a mechanic to fix? What is actually wrong? Thanks!How much will it cost to fix a severe oil leak in a 1991 Buick Regal?
can't with out knowing where the leak is could be as easy as a valve cover gasket or a rear mainHow much will it cost to fix a severe oil leak in a 1991 Buick Regal?
where is it leaking might just be the oil filter $10.00 or it might be


something that cost $1000.00
sounds like a rear main seal, i would say it costs about 600.00 to 800.00 to fix, labor is the most cost of this job.