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DSM, 3S and EVO transmissions require 2.5-3 quarts of oil. For our DSM / 3S transmission rebuilds we recommend factory Mitsubishi transmission gear oil. For stock or mildly modified vehicles, you can just use the standard Mitsubishi MTF. For higher hp, tracked, or extreme condition driven cars -- we recommend the Diaqueen 6-speed manual transmission gear oil from the 2005 Mitsubishi EVO MR. This is the best oil to use as it has the perfect blend of friction modifiers to keep the transmission shifting smoothly and helps to prevent gear failure. Gear oil choice is very important and varies based on preloads and synchro blocker ring design, therefore it is strongly recommended that you stick with this fluid for our transmissions. If you are unable to locate Mitsubishi transmission gear oil, we do offer it for sale. As an alternative, Redline MT90 gear oil will also work. Please note: The Redline MT90 may feel a bit notchy when used in colder climates. Once the fluid warms up, it should be smooth. You can find this fluid here on our website.

For transfer cases and rear ends:

DSM / 3S: 

  • Use Redline Lightweight Shockproof in Transfer Case and Rear Differential. DSM: If you have an EVOIII rear diff, do NOT use Shockproof as the LSD will not work with it. In these applications, we would recommend you use Mitsubishi LSD oil.

EVO 8-10: 

  • For an ACD T-Case, the recommended fluid is the Mitsubishi LSD gear oil. If you have a Non-ACD T-Case, we highly recommend using Redline ShockProof Heavyweight (Red). 
  • For the rear diff, we recommend the factory Mitsubishi LSD oil as the clutch packs for the limited-slip will no longer work correctly if you use Shockproof.

Transmission, ALL Mitsubishi:

DO NOT use Synchromesh, BG Synchroshift I or II, or Royal Purple. These fluids will destroy synchros and gears and void your warranty!

Shockproof in transmission:

Absolutely DO NOT use Redline Shockproof in your transmission!   

Shockproof is designed for ring and pinions found in T-Cases and Rear Diffs. If you use it in your transmission, you will break gears and ruin your synchros!

The pic below is of an EVOIII 1st gear which only had 6 months of use with Shockproof oil.  Shockproof causes odd gear failures like this one where 1 tooth in your 1st or 2nd gear will end up breaking off and missing.  We have seen a bad rash of odd failures like this with Shockproof users.

Shockproof can also cause fretting with gear teeth in your trans.  Here is a picture of an EVO 9 1st gear and input shaft after using Shockproof:

How that customers gear didn't break is amazing!  

Shockproof also has no friction modifiers, which means that synchros will be unable to work correctly and will have to work serious over-time in order to synchronize your trans correctly.  Synchros need friction in order to properly operate.  When there is no friction, they are under a large amount of pressure and will wear out very quickly.  They will also feel notchy and unpleasant to shift.  

The wax found in Shockproof oils will also plug up your small oil passages found in the synchros, shafts and center diff in your trans.  Just please don't use it!

Shockproof oils are an unbelievable achievement in engineering and a miracle oil, but only if used as intended.  Use Shockproof in your T-Case and you will never have to worry about worn ring and pinions again.  Use it in your trans, and you'd be lucky to get 6 months out of it.  It is clearly stated on Redlines instructions to NOT use Shockproof in your trans.  Take their word for it, they are the people who engineered it and know best.

Take our word for it, use the factory Mitsubishi oil in your trans at any HP level!  We don't see gear failures like this when people stick to the factory fluid.  Yes, we know, many people believe that you must have some kind of aftermarket oil for your trans if you are to push a lot of power through it.  The Mitsubishi transmission fluid is pretty amazing and will give you the cleanest gear wear, and shift possible.  

It's hard to believe that oil from the factory is best, but it is and the reason why is due to the poor engineering of the EVO 6-speed trans found in the 9 MR.  The trans broke synchros and gears at factory HP levels.  Mits had this fluid developed to allow that horrid trans to survive.  Due to this, it is the best trans fluid on the market today!

Next question we always get is: Can I use a mix of Shockproof or some other aftermarket oils with the factory fluid?  The answer is NO!  Please get away from the mentality that you must have some kind of aftermarket fluid in your trans!  Use 100% Mits fluid mixed with nothing but more 100% Mits fluid.  It works great as it is and will give you the best life and performance possible. 

We don't know who has been starting the rash of Shockproof in your trans or mixed with other fluids as a good thing, because it's not.  Please don't do it!

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