|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.
REDLINE 80W-140 GL-5 GEAR OIL We highly recommend using Redline 80W140 GL-5 Gear Oil. Their part number is # 58104.
REDLINE SHOCKPROOF HEAVY If the vehicle is going to be drag raced Redline Shockproof Heavy is an excellent oil for the transfer case but make sure temps are 45*F or warmer because the oil is not thin enough for cold weather use.
Friction modifier type additives are not necessary being that the DSM has a viscous coupling type limited slip.
IF YOUR EVO HAS A TRE REAR COVER WITH THE OIL SIGHT GLASS YOU WANT TO FILL IT NO HIGHER THAN 1/2 WAY.
96-07 EVO: Mitsubishi recommends that the rear axle that is found in the EVOLUTION be filled with their factory oil, Diaqueen LSD Gear Oil part# MZ320345 or a high quality GL-5 or higher 90w Hypoid LSD gear oil. These oils contain a friction modifier that will reduce noise associated with friction disc type limited slips.
REDLINE 80W-140 GL-5 GEAR OIL We recommend using Redline 80W140 GL-5 Gear Oil. Their part number is # 58104. For road racing applications, use Redline 80w-140.
REDLINE SHOCKPROOF HEAVY If the vehicle is going to be drag raced Redline Shockproof Heavy is an excellent oil for the rear axle but outside temps should be 45*F or warmer because the oil is not thin enough for cold weather use.
|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 is spec’d as a 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 rear differential and transfer case. Use the wrong oil and the ring & pinion gears will be ruined almost immediately from the intense heat that is generated.
|Filling the rear axle
Change the rear axle oil every 5k-10k miles. Vehicles that are being road raced require race car maintenance and all drivetrain oils should be inspected after each race and changed as needed.Road racing applications may add an additional 1/2 pint of oil to the rear axle for added lubrication and cooling. New or recently rebuilt rear axles should have the oil changed after the initial first 500-1000 miles. TRE offers an Oil Level Sight Glass upgrade for the rear diff.