I've done quite a bit of searching and reading and am still a little confused. I am tempted to put some Motul Gear 300 into my ITR when I flush the transmission fluid.

I have gathered that the viscosity of gear oil and engine oil are measured differently. Makes sense, gear for pressure, engine for temperature. However, I cannot find these standards. I want to compare the viscosity of 75W90 Gear 300 to Honda MTF of which I can't find the viscosity. However, the equivalent engine oil seems to be 10W30.

The Gear 300 is GL4/GL5 rated, the ITR transmission calls for GL4, so I can't see there being an issue. The Engineer in me wants to figure this thing out though.

Thanks for your help.

 

Gear oil is meant to be used in drivetrains where the differential is separate from the transmission. It's a lot thicker than transmission fluid, and shouldn't be used in a Honda transaxle where the transmission and differential are housed in the same casing. Many people, myself included, have mistakenly used gear oil in place of transmission fluid, and it's not something I would ever do again or recommend. Stick to Honda MTF or GM Syncromesh Friction Modified in a Honda transaxle. If you don't have an easy source for either of those two, make sure whatever you use is clearly specified as "manual transmission fluid" and not gear oil. If you can't find any MTF of any kind, 10w30 works as a replacement, but lacks the additives that prolong the life of your synchros. Again, unless you drive something that's AWD or RWD, you don't need to worry about gear oil, just stick to MTF. If you're set on using a Motul fluid, check and see if they have an MTF.

 

Thanks for the comment, and warning. Appreciated!

From my understanding 75W90 gear oil should be about the same thickness/viscosity as a 10W40 engine oil. However, I just can't find the standards which describe both gear and engine oils and how they're measured.

As far as I have been able to tell, Honda calls for GL-4 in the transmission, which is in fact Gear Lubricant 4. GL designation covers manual transmission and complex gears. I think it should be fine, I am just trying to sort through it all.

I found the following graphic:


Modified by Scotty2H at 5:13 PM 6/24/2008


Modified by Scotty2H at 8:40 PM 6/24/2008

 

i have a 99 si i flushed out my tranny and put in some GM syncromesh.. i had a slight grind going into 5th before i changed the fluid. my tranny shifts and syncs up so much better now. you can get it from any gm dealer or usually those drive through oil change places

 

Well for anyone who cares, and it doesn't seem many do!

I installed the Motul Gear 300 this afternoon. Initial impression are positive . The gear box is significantly smoother than the old Honda MTF and even than what I recall of the MTF when it was new.

Word of warning however, the stuff stinks, badly. Only open and pour in a well ventilated area, as in outside.

I'd still like to know what the Honda MTF actually is if anyone has that information.

 

^^GM syncromesh x2...old school and still works the best

 

has anyone tried honda's new "advanced" mtf...apparently its supposed to be similar to the syncromesh.

i have it in my car and i did find that it made smooth shifts easier.