What fluid to use in tranny and transfer case?

[Ultraspontane]

I've noticed the BII is a little harder to shift when it's cold out, becomes easier once the truck warms up thoroughly. I've also noticed noise from the transfer case when I'm coasting along in gear at certain speeds. IT sounds like a metal on metal grinding noise. The sound goes away when you're on the throttle, it's only while decelerating while in gear and 4x4 engaged.

I'm going to change the fluids for the tranny and t-case. I've read conflicting reports on what type of oil should be used in the Mitsubishi FM146 and stock transfer case. Some say use standard gear oil, and some say use ATF. What is up with that? ATF and gear oil are very different types of fluid.

What should I use? Again, it's a 1989 with the Mitsu FM146 5sp, and the stock transfer case.

 

[adsm08]

Ok, to clear this up.

The FM transmissions used 80-90 gear lube

The M5OD uses Mercon V ATF

The transfer case (all of them) are currently spec'ed as taking Motorcraft transfercase fluid.

Motorcraft transfercase fluid is Mercon V with limited slip differential friction modifier added. It is really only important to have it in an E-shift case that was made after 2002. It won't hurt to put it in an earlier unit though.


In conclusion, Ultra, you need a few quarts of 80-90 and a few quarts of ATF.

 

[wildbill23c]

Here's right from the Haynes Manual #36070

 

[Ultraspontane]

Thanks guys. Gear oil in the tranny and ATF in the t-case. Got it.

 

[adsm08]

I would like to point out that Dex 3 through 5 and Mercon/ Merc V are compatible with Dex II.

 

[wildbill23c]

I would like to point out that Dex 3 through 5 and Mercon/ Merc V are compatible with Dex II.

I didn't know that, thanks for the info. I always thought they were all completely different.

 

[Ultraspontane]

Just to get back to this topic, from what I can tell, it's common for a manual trans to shift harder in cold weather. There is noise while shifting in the cold, too. It goes away completely after about 15 mins of driving and everything is warmed up. I'm talking about below freezing temps.

Is there a type of lubricant that would work better in the winter time? Be it an additive, a lower viscosity oil, synthetic, etc. Or do I just have to listen to my tranny grind while shifting until it warms up?

 

[adsm08]

I didn't know that, thanks for the info. I always thought they were all completely different.

Yeah, our bulk ATF at work has a huge list of everything it is compatible with.

The only things not on the list are Dex 6, ATF+4, Mercon SP and LV and Ford's Premium trans fluid. Pretty much everything else in the world works with MercV.

 

[wildbill23c]

^^That's good to know that its pretty compatible fluids.

As for that transmission noise could be that the transmission oil being cold and thicker just isn't lubricating certain parts enough so it makes noise, mine kind of whines when its cold but goes away after the transmission is warm.