GL5, Synthetic and Syncros

[Narcoleptic]

I've seen some posts on other forums (especially Subaru forums) regarding the use of GL5 rated gear oil in manual transmissions. There are people making claims that the sulfur in the oil eats the brass syncros in the transmission. They also advise against synthetic as it doesn't "stick" to the gears as well as dead dino juice.

While I don't put much stock into this, I was interested if there is indeed any truth to these statements.

 

[TooSlick]

Lots of free advice from self proclaimed, "oil experts" on the Internet ...

It's almost worth every penny you pay for it

TS

 

[doyall]

From this thread http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=4;t=000225 started by Molakule. Both parts I & II are excellent reads.

quote:

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GL-5; Specified for hypoid gear service but with shock loads and severe service operation. Usually meets Mil-L-2105D and in most cases, is the multipurpose automotive gear oil. Most 75W90 to 75W140 grades meet the GL-5 classification. This grade has a high level of Extreme-Pressure additives that could be mildly corrosive to nonferrous parts, such as brass, bronze and aluminum parts. Most of the modern GL-5 lubes contain metal deactivators that prevents attacks by the extreme-pressure additives. In addition to EP additives, these lubes contain rust inhibitors, defoamants, friction modifiers, thickeners, and Viscosity Index Improvers.
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=21;t=000029

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[ November 19, 2003, 06:44 PM: Message edited by: doyall ]

 

[GSV]

Our 99 Legacy's owners manual specifically recommends GL-5 for the manual tranny.

Other companies spec GL-4 like Nissan and VW.