Review on Lube Locker Turbo 400 TH400 Transmission Gasket: Reliable and Proudly American-Made by Marklen Baeskens

Lube Locker THM400 oil pan gasket check. Lube Locker advertises this gasket as having everything you need: a metal backing and 2 different gasket materials. Sounds very good. When inspecting a new gasket, they seem to have misjudged the actual sealing surfaces. The THM400 sump does NOT have a 100% flat flange gasket. The HOUSING/GEARCASE flange is flat (100% smooth) BUT the transmission pan is NOT a flat flange (it has both raised and flat areas). The raised portions of the oil pan flange compress the gasket with the flat areas of the oil pan gasket around the oil pan bolts. The problem with the Lube Locker THM400 washer is that the washer is not thick enough to fit BOTH the flat and raised surfaces of the tray. It is estimated that this gasket is a uniform 2-3 mil thickness AND ALSO not shaped to match the sump mating surface. This gasket design may be better suited to the typical double machined surfaces found on some thermostat housings, carburetors, etc.