AMSOIL MTF or MTG?

[simons]

I recently changed my transmission fluid in my 08 EVO X and instead of using OEM Mitsubishi NEW MULTIGEAR OIL (GL-3, 75W80), I used AMSOIL manual transaxle gear lube (MTG 75W90). The product recommendation from AMSOIL is to use their manual synchromesh transmission fluid (MTF 5W30).

Am I okay with using the MTG 75W90 or do I need to change that and put in what AMSOIL recommends which would be their MTF 5W30?
I don't think so because the viscosity of their MTF is way different than the OEM 75W80.

 

[bmwtechguy]

The MTF is roughly equivalent to a 5w30 engine oil viscosity and says so right on the bottle. If that is what is recommended for your Mitsu, then I would use it with confidence. You see, the 75W-80 viscosity grade recommended by the OEM is a gear oil viscosity rating which is equivalent to a 5w30 engine oil viscosity. The MTG that you used is closer to a 5W-40 or 10W-40 engine oil viscosity, so it is a bit heavier, especially at operating temperature. So it may shift a bit more sluggishly in cold weather or all the time. If it shifts ok, it may be fine to keep in there, but don't expect Amsoil or Mitsu to back you up if you have a warranty claim on the gearbox if you have the wrong viscosity fluid in there. For a chart to see how different viscosity ratings overlap see this page on bitog:
(compare the SAE gear oil to SAE engine oil)

http://www.bobistheoilguy.com/visc.html

 

[simons]

I talked to a tech guy at AMSOIL and he said that the 75W90 is quite a bit thicker than the MTF 5W30. And if anything, it might make the transmission run hotter due to it being thicker. He also said that he wouldn't drive around with it in there.

Apparently AMSOIL produces their product lookup tab based on what the manufacturer recommends. So, I ordered the right stuff this time. AMSOIL's MTF 5W30. I'll keep the 75W90 in there until the good stuff gets here and will swap it out. I don't think any transmission damage would occur in a couple of days.

 

[Pablo]

Cool I see you figured it out! This might help when thinking about viscosity comparisons:

http://www.lubrizol.com/products/automotive-gear-oil/J306.asp

http://www.infineum.com/information/viscosity.html

 

[msparks]

It won't hurt anything, though you could have trouble shifting in cold weather.

 

[simons]

I didn't realize how much a difference the viscosity makes when dealing with transmission oil. I just hope the thicker oil I have in there now didn't do any damage. I'm going to try to avoid driving a whole lot just in case. I'm crossing my fingers that the MTF 5W30 gets here this weekend.

 

[Pablo]

Trust me, you didn't damage anything.

 

[cos]

So how does the trans shift with the MTG compared to the stock Mitsubishi stuff?

 

[simons]

I haven't noticed a significant difference in shifting. It's a little better.

There's a dude on evom.net who goes by the name Oil Doc who I guess is a distributor for AMSOIL and he says that he recommends the MTG for ALL EVO's because of the way they're driven. If you drive like a granny, a simple daily commuter, and don't drive hard, to use the MTF. But if you drive it the way it's meant to be driven, to use the MTG. He says shifting may be a little harder when it's cold, but I will have more protection at higher temperatures and shock loads.

He said the MTG will work fine and that I should just send back the MTF when it gets here and eat the freight charge.

 

[mechtech2]

It sounds like 'Oil Doc' has pretty fair advice. ^^

 

[simons]

Yep. He said all but 1 of his EVO X customers is running MTG with no problems. The 1 guy who isn't, drives like a granny and is using the MTF. I think MTG is the way to go.

 

[MolaKule]

Quote:
I used AMSOIL manual transaxle gear lube (MTG 75W90). The product recommendation from AMSOIL is to use their manual synchromesh transmission fluid (MTF 5W30).



Just curious as to why you went against the recommendation?

I doubt you will damage anything by using the thicker gear lubes, since they each have about the same additive levels. Your shifting would probably be rather "sticky" until the tranny warmed up.

Read some of BITOG's white papers such as:

Quote:
You also have to consider the viscosity of the fluid that the transmission was designed for. The spectrum now ranges from ATF to 75W90 viscosities and therefore a synchromesh GL4 Manual Transmission Lubricant (MTL) can be any viscosity from 7.0 cSt (ATF equivalent viscosity) to a 75W90 type viscosity of approx. 14.5 cSt, and contains special friction modification additives for synchronizer assembly engagement.
brass/bronze, or steel-steel materials.

Current MTL GL4 viscosites are:

1. ATF Series - Type; 6.5 to 8.5 cSt (Equivalent ATF viscosity; Note: ATF additive package is weak compared to most GL 4's)
2. Synchromesh Series -Type; 9.3 - 9.5 cSt (such as Amsoils MTF, Texaco's MTL, Pennzoil's Synchromesh, GM and Chrysler's Synchromesh)
3. 75W85 Series-Type; 9.8 to 11.5 cSt ( Redline's MTL, RP's Synchromax LT, Nissan's MTL, Honda MTL, Castrol Syntorq LT)
4. 75W90 Series-Type; 12.8 to 14.5 cSt (Amsoil's MTG, Redline's MT-90).

 

[simons]

I heard other evo x owners are using the MTG instead of the MTF with good results. And that a thicker oil has added protection during aggressive driving. I don't granny drive so I thought I should use something geared more towards that.

Oil Doc, the guy I talked to on evom.net, talked to several driveline (transmission) specialists and they agreed with the recommendation of using the MTG if you drive an evo the way its meant to be driven.