Use the correct oil

89-94 DSM: The recommended oil for the rear axle of all the Mitsubishi DSMs GL-5 90w Hypoid gear oil.  If the vehicle is going to be drag raced, road raced or being operated in climates that are 45*F or warmer we highly recommend using Redline Shockproof Heavy for it is an excellent oil for the rear axle. Also, you may use a GL-5 or higher Hypoid gear oil that has an ISO of 280-460 if temps are 45* or warmer because of the heat load that is generated is sufficient enough to thin the oil out so it doesn't aerate, web, foam up or cause lubrication issues due to the oil being too thick to perform properly. Friction modifier type additives are not necessary being that the DSM has a viscous coupling type limited slip. If do not have access to the recommended oils you can use any high quality straight GL-5 or higher Hypoid gear oil that is a straight 90 weight or an ISO index of at least 220.

OIL VISCOSITY INDEX CHART

96-07 EVO: Mitsubishi recommends that the rear axle that is found in the EVOLUTION be filled with the factory oil, Diaqueen LSD Gear Oil part#  3775610 or a high quality GL-5 or higher 90w Hypoid gear oil. If vehicle is being raced in climates that are 45* or warmer you may use a high quality GL-5 Hypoid gear oil that has an ISO of 280-460 because the heat load that is generated is sufficient enough to thin the oil out so it doesn't aerate, web, foam up or cause lubrication issues due to the oil being too thick to perform properly. Those who drag race should use Redline Shockproof Heavy. For road racing applications where increased action from the factory limited slip differential is desired, use Redline 80W140 NS for this oil does not contain the limited slip modifiers that reduce the effectiveness of the clutch pack style limited slip that is found in the EVO. If do not have access to the recommended oils you must use a high quality straight GL-5 Hypoid gear oil that is a straight 90 weight or an ISO index of at least 220.

OIL VISCOSITY INDEX CHART

Do not use GL-3/4/5 gear oil in the rear axle

When it comes to the rear axle that is found in the Mitsubishi vehicles, do not make the fatal mistake of using any oil that claims to be a magical GL-3/4/5 gear oil. These one size fits all type oils are not recommended anymore than a one heat range fits all spark plug and they are notorious for ruining the ring & pinion gears.

Hypoid ring & pinion gears

The rear axle features hypoid gears, commonly referred to as ring & pinion gears. The word hypoid is short for hyperboloid which refers to the design of these gears. Hypoid gears don’t share a common axis, run quiet (for the most part) and they are very strong by design. Yet by this design, the gear teeth must slide across one another during their meshing and this is why you must use the correct gear oil with at least a GL-5 rating in the transfer case. Use the wrong oil and the transfer case and the ring & pinion gears will be ruined almost immediately from the intense heat that is generated.

Filling the rear axle

Oil must be level with or slowly flow back out of fill/level plug.

EVOLUTION OWNERS TAKE NOTE: We recommend that the rear axle oil level be checked again after you have driven the car a few miles at speeds over 25mph to allow the oil to properly coat everything. Drive and recheck the oil level.

Change the rear axle oil every 5000-10000 miles. Vehicles that are being road raced require race car maintenance and all drivetrain oils should be inspected after each race and changed if the oil is dark or stinky. Road racing applications may add an additional 1/2 pint of oil to the rear differential for added lubrication and cooling. New or recently rebuilt rear axles should have the oil changed after the initial first 500-1000 miles.

 © 2008 TRE