jkfox121

I was looking into purchasing some Motul Gear 300 for my tranny. It is rated GL-4 and GL-5, does this mean I can use it in my tranny and not yellow metals? Can I use it in my diff?

Thanks,

Joe

xviper

GL-5 gear oils are for our diffs. You shouldn't be putting this into the tranny.

Slows2k

Check out the oil journals for more info:
https://www.s2ki.com/forums/index.php?showtopic=195574


Moved to UTH

jkfox121

The reason I ask is because the bottle says both GL-4 and GL-5. How does it meet both specs??

Thanks,

Joe

xviper

Slow might be able to elaborate better but this is the way I see it.
Honda does not recommend a GL-4 fluid in our trannies either. I think the Motul has properties that make it OK to use in a rear diff that requires a GL-5 rating and this may be the killer for our trannies. You need the heavy sulfer component to make it work in our diffs, but then, that same sulfer is what the yellow metals in the tranny doesn't like. However, if you have an '04 car where the syncros are made of different stuff, I guess you might be OK. But then again, you wanna risk a very expensive tranny on the "possibility" that the fluid won't harm it when you already know of many fluids that will do nicely?

Slows2k

GL-4 is an older spec than GL-5. An oil can meet both.

I wouldn't risk the carbon synchros in a 04 -05 trans with any other oil except Honda MTF. You're still under warranty, I wouldn't risk damaging a VERY expensive gearbox by using the incorrect oil.

At last year's SESM, A Lubrications Engineers rep wouldn't reccomend using any LE product in the 04-05 trans. They don't want to risk the liability of their oil not meeting the spec for carbon synchros.

jkfox121

I am using GM Syncromesh FM, do you know if there is any known risk with this tranny fluid or MT-90? I have been reading the "Oil Journals" and couldn't find anything saying they had negative effects on the carbon syncros. Thanks for the info,

Joe

Road Rage

Motul is certainly confusing things with their GL4-5 rec. These are almost always mutually exclusive specs. The EP compounds added to make GL-5 are primarily sulfurous - which can be in reactive or non-reactive forms. It is the reactive sulfur that poses an immediate risk to yellow metals, but sulfur in the presence of heat and water vapor can form - anyone? - yes, weak sulfuric acids. Over time, these can etch metal, esp since tranny fluids are not replaced as often as engine oils. Plus, engine oils are formulated to deal with acid buffers, since US fuel is high sulfur, and water and heat are by-products of combustion.

Personally, I would not use 300V in the tranny, for sure. It does not have the right COF properties, and esters in long service life situations trouble me these days - hydrolysis and all that. While I used to be a big supporter of G-V esters, recent tribology has shown how modern lubes have made advances, esp. in the add packs, that make the base stock much less important than it once was.

My favorite diff fluid is a highly refined GII+ base stock with spectacular, proprietary additives (LE-607); their 8130 engine oil is a GII+/GIV blend, but has performance that matches or exceeds the best full syns (again, the add pack is unique), and I like GM's Syncromesh FM tranny fluid, which is a synblend with rather light viscosity.

jkfox121

Thanks for the info. I switched my tranny onver to MT-90 as GMSFM wasn't working out to well for me. Personally I like the MT-90 better.