Rover Range
Full Access Member
I've only seen two rear main seals that were bad.I'd get a second opinion to be sure unless you know those guys well enough not to stick it to you when the issue was really a valve cover gasket as mentioned. During my research prior to purchasing I don't think I even read about a rear main seal go bad but I'm sure they are out there. Nothing like the coolant system problems. I had valve cover gasket leak oil and it would smoke at the end of the off-ramp.
Both vehicles had this weird groaning noise.
There was actually a vacuum leak through the rear main seal into the torque convertor cavity. I could feel engine vacuum at the transmission bell housing weep hole.