Polytetrafluoroethylene (PTFE) rubber is the ultimate in rear main seal design and material because it holds up well at high temperatures and is compatible with a range of engine fluids.

Seals made with PTFE rubber have a unique “lay-down lip” contact sealing surface that can run on undersize shafts, seal minor shaft imperfections and virtually eliminate shaft wear. They must be installed dry with no pre-lubrication of the sealing lip.

Lay-down lip PTFE rubber rear main seals are available exclusively through Federal-Mogul’s National® Oil Seals product line.