Cost to replace rear main seal, how long to fix it, leaks front and back engine

Just the facts: No engine size listed but this part will apply to both options .. Given the year model and suspected mileage this repair is hit or miss at best! .. Internal engine wear such as crankshaft main bearings, which will allow excessive crankshaft movement inside the rear main seal, in combination with worn piston rings, which will allow excessive compression 'blow-by' blowing oil out of the seals, usually makes this repair beyond reasonable expenditure as the same problem will likely return in a short while .. Just so you are aware of what is likely to happen if the work is done... Recommend engine breathing system inspection and necessary parts replacement including the PCV valve and components to insure proper operation.. This may help with oil consumption.