Various fluids meant to provide a friction reducing film between moving parts. Highly viscous ones don't come out of denim jeans
Amsoil PCO Semi-Synthetic Diesel Oil. Personally used in a customers '01 Dodge Cummins with exceptional results. Combined with regular oil analysis he was able to achieve 20,000 mi oil change intervals w/filter changes at 10,000 mi. Results will vary based on use and abuse. Oil analysis is highly recommended on all vehicles as a part of regular maintenance. It provides information that can literally save your hard earned money through predictive maintenance, rather than fix it after it has broke and left you stranded.
For all of you "knuckleheads" out there. Amsoil AHR Synthetic MC oil. Good for use in air cooled motors due to its high viscosity. Please note that you may require a mule to kick for you.
For those of us with the luxury of modern liquid cooled engines. Amsoil MCV Synthetic MC Oil. Compatible with wet clutch systems due to the lack of friction modifiers.
Located in Superior Wisconsin, Amsoil began with founder Al Amatuzio an ex-armed forces pilot. Check out Amsoil for all your lubrication needs and then call us: Dealer #1820126