If you go to their web site they claim that their MLS series Perma Torque head gaskets need no retorqueing.
http://www.federal-mogul.com/en/Afterma ... torqueMLS/
Torque Retention and Extra Support for Lightweight Designs
The preferred technology for many late-model vehicle engines is multi-layer steel (MLS). Recognizing that replacement applications typically offer less-than-ideal sealing conditions, Federal-Mogul engineers created an MLS technology that addresses the true aftermarket repair environment. The result is the Fel-Pro® line of PermaTorqueMLS products.
PermaTorqueMLS head gaskets offer a wide range of benefits, including:
* Strategically placed sealing beads that help eliminate leak paths
* Extra-strong stopper layers that provide superior primary combustion sealing (where applicable)
* Full-hard stainless steel material that maintains its shape despite thermal expansion and scrubbing between the block and head
* A unique, application-specific coating that enhances sealability
What’s more, Fel-Pro PermaTorqueMLS head gaskets provide the torque retention required to maintain positive contact pressure between head and block over the life of the repair.
MLS technology is specified on most current U.S., European and Asian engines in production.
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http://www.federal-mogul.com/en/Afterma ... rmatorque/
Sealing Solutions for No-Retorque Designs
Fel-Pro PermaTorque head gaskets are the professional’s choice for reliable, no-retorque type head gaskets. High-density materials and superior design specifically for the aftermarket repair environment demonstrate Fel-Pro’s commitment to providing sealing solutions that perform under pressure.
Fel-Pro PermaTorque head gaskets provide an ideal no-retorque design. These head gaskets compress enough at installation to conform to, and seal, minor surface imperfections while minimizing relaxation and maintaining adequate clamping force over long time periods.
Get the no-retorque head gasket that performs under pressure.
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http://www.federal-mogul.com/en/Afterma ... atorqueSD/
The Premium Choice for Severe-Use Applications
Premium Fel-Pro PermaTorqueSD head gaskets are a superior choice for engines in severe-use situations, such as taxis, RVs and construction vehicles. Intended for non-multi-layer steel (MLS) applications, these ruggedly engineered head gaskets provide a variety of benefits, including:
* Increased armor thickness
* Stainless steel armor material
* Special flattening operation
* Enhanced body core thickness
* Printoseal® sealing beads
* Proprietary coating
Fel-Pro PermaTorqueSD gaskets are a superior sealing solution for hardworking engines.
