GL5 Gear Lube

I know it has been talked about pretty good, but it seems in all the threds it hasnt come to a all around consensus GL-5 it is safe for our Xj rear ends.
Any knew updates?
Anyone find out if there is for sure brss or bronze in the rear?

 

AFAIK GL-5 hypoid gear oil is what's recommended for our bikes...
GL-4 would probably break down a lot sooner.

 

My haynes manual says gl4 or 80w90.... Just didnt know if since the manual is old that the recommendations could be outdated cause of technology?
So my Haynes manual is wrong then?

 

I drained my gl-5, till I find out for sure, man I know I am anal but you know....

 

Ahh drat.. my bad, it is GL-4. Now i'm gonna go nuts trying to remember where I came up with GL-5.

I still don't think GL-5 would be a problem though..

 

From WikiPedia:

"GL-4 and GL-5 are standards set by the American Petroleum Institute for gear oils. GL-4 are intended for axles with spiral bevel and hypoid gears operating under moderate to severe conditions of speeds and loads. They are also suitable for sychronized manual transmissions when MT-1 gear oils are NOT recommended. GL-4 should be used in limited-slip differentials. The GL-4 generally indicates "Limited Slip" properties in the gear oil; sometimes abbreviated as LS.

GL-5 is indicated for high-speed/shock loads and low-speed/high-torque conditions. GL-5 also has multi-purpose or mild EP (extreme) properties too. GL-5 is often seen with the MT-1 designation too.

MT-1 indicates lubricants intended for NON-sychronized manual transmissions. MT-1 indicates the additional additives necessary to protect against thermal degradation, component wear and oil-seal deterioration which are not requirements by GL-4 or GL-5 approval.

GL-5 is not the latest and greatest improvement over GL-4; unlike oil classifications where higher classification numbers mean tougher standards and backward compatiblity. It is important to know what type of gears you are lubricating, their applications and follow the manufacturer's recommendations! More information can be found at www.api.org."

All that being said, the biggest flap is over the high sulfur content in GL-5 oil causing erosion of brass, bronze and some aluminum alloy castings.
If GL-4 is recommended, then I would stick with GL-4, even though it is becoming harder to get. My Norton calls for GL-3 but I think that's all that was available at the time. (Good thing I have unopened stash.)

 

OK so I drained the GL-5 out, now do I need to throw some gl-4 in turn the rear wheel a couple hundred times and the drain and refill to flush that gl-5 out?
The Gl-4 at Napa is sta-lube. it is 85w90

 

diesel fuel makes for a V good flush media. As it has no solvents that can linger to degrade the new oil fill.

 

I flushed mine with starter fluid which would evaporate completely,
(hoping to dislodge metal filings)
But hold on !! GL-5 is the modern BOAT standard, what with 200 HP, shock loads engaging forward and reverse, a water dispersant, and all in an aluminum housing with some bronze.
Besides, I bought 7 tubes at $0.50 each at a closeout. . .
It's Kendall.

 

See why I like chain drive?

 

Well heck I will just swap someone a 650 maxim for a 400 or 550 then! any takers I just shined it up with MOthers this after noon.

 

Im gonna try that diesel flush.