The purpose of this article is to compare various styles of head gaskets that are available for the 6.5L diesel engine.

• Smallest fire rings

• Brittle fire rings

• Cant be used when o-ringing the block

• Ok for totally stock, repair scenario with tty bolts. Fel-Pro targets the service/repair environment

• As of 2025, Fel-Pro is discontinuing their 6.5L head gaskets

• Thicker, Heavy Duty fire ring

• Our recommendation if using standard head gaskets

• Can be used when o-ringing the block

• Composite gasket material

• MLS (Multi-Layer Steel)

• There are a few revisions of MLS over they years. Old tales do not apply.

  • Important to note the Cometic gasket completely changed in 2023 and any information from the internet before late 2023-early 2024 is not applicable. Quadstar did the initial testing and design revisions of this gasket from day 1.

• The embossed outer layers of these head gaskets meet the demands of a variety of harsh sealing environments, load conditions, and surface finishes. The MLS Gasket (Multi-Layer Steel) features an active combustion seal on multiple layers.

  • The thickness of the center layer can be changed to change the overall thickness of the gasket. We recommend using the thinnest head gasket suitable for your needs.

• A surface finish of 50 RA (roughness average) or finer, is recommended for a proper gasket seal. Anything rougher could conflict with the gasket design.

10-15 thou protrusion recommended

Copper wire ONLY