gear box and final drive oil

[gfritzmeier]

this has probably been answered many times but I can't it so here goes again. I'm changing oils in transmission and final drive on 2003 cal aluminum.  Do I use the same oil in both. I think is SAE 80w/90 but just want to make sure and is any particular brand preferable???   
Thanks,
Fritz

[twhitaker]

If you are going to use a GL4 oil in the final drive make sure you add some M2SO4.

[gfritzmeier]

  ???????????

[menzies]

I have used Mobil 1 synthetic gear oil in both trans and final drive in 3 different Guzzi's with good results. I believe it is 85/90, would have to go out and check.

[twhitaker]

Final drive gets 220cc oil and 30cc molybdenum disulfide (moly, M2SO4). Moly is an extreme pressure additive. What I've been led to believe, the GL4 is mineral based while GL5 is synthetic and does not need the moly.

[gfritzmeier]

Thanks I think I finally get it. I'll be using GL4 in tranny and GL5 in rear end.  I read elsewhere that synthetic in my year bike can give me some major tranny problems because of some bearings that are coated in plastic? I won't take that chance seeing that I had a friend that had to have a major overhaul on a new Harley after only 15K miles.

[rocker59]

Mobil-1 75w90 is what I've used for a couple decades, now.

[Two Checks]

GL5 can be either dino or syn.

[rodekyll]

On my EV (same power train) I use the same lube in both for the sake of simplicity.  Yes, sometimes synth finds exits around seals and plugs.  Sometimes it's dirty seal surfaces and old plug washers.  Sometimes it's the nature of the beast.  I swirched to redline heavy shockproof and used it for years until it started leaking.  Cleaning the seal surfaces and changing the washers didn't help.  I purged it and went back to dino -- no more leaks.

[Dilliw]

If you put the moly in the rear you can tell which end is leaking :)

[Bobolink]

Here's some useful information on the matter.

http://www.lastgreatroadtrip.com/wp-content/uploads/2010/11/gear-oil-comparison.pdf

[oldbike54]

 What does the owner's manual call for ?

  Dusty

[gfritzmeier]

Dusty,
Owners manual calls for gearbox="Agip Rotra MP SAE 80 W/90" oil   &
Final Drive(bevel gear lubrication) "Agip Rotra MP SAE 80 W/90" oil
                                                "Agip Rocol ASO/R" oil
                                                ("Molikote type A")

This is all like a foreign language to me.  I also read that 2004 and prior years shouldn't have and synthetic in the gearbox because ome of the bearing are plastic coated and synthetic eats the plastic away and then ya got real problems.   Today I purchased some BelRay hypoid grar oil 80W-90 for shaft drive unit that meets or exceeds API GL-4 & GL-5 requirements.  I feel comfortable putting that in Final Drive but not so sure about putting it in the Gearbox. I just don't want to make a mistake that could cost me in the long run.

[Chuck in Indiana]

Dusty,
Owners manual calls for gearbox="Agip Rotra MP SAE 80 W/90" oil   &
Final Drive(bevel gear lubrication) "Agip Rotra MP SAE 80 W/90" oil
                                                "Agip Rocol ASO/R" oil
                                                ("Molikote type A")

This is all like a foreign language to me.  I also read that 2004 and prior years shouldn't have and synthetic in the gearbox because ome of the bearing are plastic coated and synthetic eats the plastic away and then ya got real problems.   Today I purchased some BelRay hypoid grar oil 80W-90 for shaft drive unit that meets or exceeds API GL-4 & GL-5 requirements.  I feel comfortable putting that in Final Drive but not so sure about putting it in the Gearbox. I just don't want to make a mistake that could cost me in the long run.

Not to worry. Put her in there. What we're talking about here is bearings that have plastic cages. From memory, it was in the 90s through about 02 transmissions. As Rocker says, though.. I ran Mobil 1 in a Centauro for 40 thousand miles without issue. Maybe it was a different synthetic oil that made the difference? I don't know, but I'm pretty sure that the 04s were ok with syn. of all kinds.

[gfritzmeier]

Chuck, Mine is a 2003 Aluminum and I thought I read that they still had the plastic cage tranny bearing but haven't been able to verify that one way or the other.