The 90 4door Montero that I recently bought to replace my V6 Raider is driving better in every way except for the transmission. 2nd gear is really irritating me. Recent posts indicate that I am far from alone. Anyway, I have seen Red Line MTL recommended to smooth it out. It certainly makes my Miata happier (2nd synchro worn out there too; both vehicles over 100,000 miles), but I have also seen posts that indicate GL4 to be very bad for Montero synchros. Those posts said GL5 is needed. Checking the Red Line web page, I see that MTL is a GL4 lubricant.<P>Comments? Recommendations?<P>Thanks,<BR>-Rod

Nope you got it wrong. GL4 are preferred anytime a syncros are present. At least on Japanese manual tranny. <P>GL5 are preferred for Hypoid gear use such as differential gear. <P>You would be fine with MTL or MT-90. Use MTL if you live in colder climate, Use MT-90 if you live in warm climate.

So, what's everyone currently using, anything available off the shelf at the local auto parts? Everything seems to be GL-5/for limited slip...

GL5 will eat up your synchronizers,as they are bronze. I couldn't find any in my area,and use 20w50 motor oil with great results. I'm sure that I will get some feedback on this,but the shifting improved a lot,and after 350,000 miles,that's good.

85w gear oil. According the back of the bottle it is good for GL3, GL4 and GL5 applications.

Most I've seen said good to top off when GL-3,4 are used,not to replace. Synthetic may work,though.

Sta Lube (?) At NAPA is the only GL-4 lube I have found on the shelf. Stay away from any that say GL-4 & GL-5 compatable, they are Gl-5 oil, admittedly a better high pressure gear lube, but hard on synchros. There has been lively debate here about this, but Mitsu directly specifies GL-4 for the x-fer case with GL-5 for the diffs, must be for a reason.

I keep reading the same thing about GL-5 and brass synchros. I'm glad I did some research because both My user manual and factory service manual specify "GL-4 or higher" for all fluids. Guess I'll order a few quarts of MTL or MT-85, or go cheap with a jug of the StaLube 85-90, seems a little thick but reviews are good. The old stuff in there now takes a few mins to warm up when it's freezing anyway (prolly used the same stuff last time, but that was a loong time ago when i first got the truck).



Thanks,
~Mac

GL5 in front and rear diffs, GL4 in tcase and trans. Redline MT90 is GL4 and puts those syncros in their happy place.