Gearbox oil question

[sparkydave]

I stumbled onto a thread over in that Triumph forum (no, I'm not going over to the dark side /ubbthreads/images/graemlins/grin.gif), and came across a post talking about GL-5 gear oil damaging brass synchro rings. Well, that got me thinking because I put GL-5 into my gearbox. On the one hand, I haven't noticed any problems after 2 years and 2000 miles, but does anyone have any idea of how much brass is in a 1500 gearbox?

 

[Matthew E. Herd]

A further question: If not brass, what material do the new manual transmissions use?? That comment makes no sense to me. Also, I've been using (first hypoid gear oil, followed by redline synthetic) GL-5 rated oil (if I'm not mistaken, the redline is GL-5 also, and recommended by Moss). At any rate, when I had trans failure after about 2100 miles (some racing), the teeth blew clean off the input shaft gear and the matching laygear. However, there appears to be absolutely no damage/corrosion/etc on the synchro rings and other parts which would ordinarily be annihilated under a tremendous shock that caused the forward U-joint to also destruct. This argument really makes no sense. However, this leads us to the possibility of conducting an experiment to determine what would happen if the parts of a transmission were soaked in various newer oils. Since I have a transmission ... I may be willing to conduct the test once I get around to dismantling it.

 

[aeronca65t]

Like most transmissions, your's has brass syncros and some brass bushings.
GL-5 is designed for hypoid gears (like rear axles). This is due to additives in it.
GL-4 is meant for manual transmissions like your's.
Some manual transmissions are approved for GL-5.

Despite all this, I'm running Valvoline Synthetic GL-5 gear oil in my 1500 racer. It was recommended to me and I am very pleased with it...shifts much smoother. I'm not sure what affect it is having on internal parts (but I change trans oil about every 10 hours). Redline makes sythetic gear oil too, also highly recommended among racers....but not sure if it's Gl-4 or GL-5.

Here's what Castrol has to say on the subject:

We would recommend the use of a GL-4 rated fluid such as Castrol Hypoy 80w-90 (Not to be confused with Hypoy C 80w-90 which is a GL-5 product). A GL-4 oil may be employed in certain manual transmissions whereas a API
GL-5 gear oil designates service of hypoid and other types of gears commonly found in rear axles. These differences are mainly distinguished by the level of active additives employed in the product. Different applications require different additive levels and different component materials can be affected by the levels of additives present in the
lubricant.
Having said that GL-4 and GL-5 gear oils are not compatible and manufacturer's recommendations should be adhered to. They cannot meet the same specifications and the product performance and tests are different.
Typically, a GL-5 gear oil will have about 2 times the active additive level of a GL-4 product. This additional additive can cause problems with yellow metals like brass or bronze.

Consumer Relations
Castrol North America
1-800-462-0835
castrol@idea-factor.com

 

[sparkydave]

Interesting information, to be sure. The oil I have in there says on the label that it meets GL-3, GL-4, AND GL-5 specifications, just to add to the confusion. If you look through Autozone at the collection of gear oils, they all say GL-5. What's even more interesting is that some new manual transmissions use automatic transmission fluid, but I'm not planning on using that in the Midget. I have heard some good things about the Redline stuff that Moss sells, so I might consider putting that in. Thanks for the info, and I might be thinking about changing over at some point.

-Dave

 

[RobSelina]

[ QUOTE ]
I have heard some good things about the Redline stuff that Moss sells, so I might consider putting that in.


[/ QUOTE ]

Dave - I'm running the redline synthetic in the trans and axle and like it a lot. Quiet and smooth....