MikTip

"Modern gear lube additives contain sulfur-phosphorus components that are thermally stable, and are noncorrosive to bronze and other nonferrous metals."<ul><li><a href="http://www.practicingoilanalysis.com/article_detail.asp?articleid=496&amp;relatedbookgr oup=OilAnalysis">http://www.practicingoilanalysis.com/article_detail.asp?articleid=496&amp;relatedbookgr oup=OilAnalysis</a</li></ul>

MikTip

Sure got quiet around here.... (crickets chirping in back-ground) ;O)

VAP

But I've still "personally" got to give the nod to API's rating as I dont think Mobil Oil would miss out on 90% of the transmission market which is what GL4 spec transmissions own. Secondly Mobils specific statement saying the EP additive sulfur in their oil is erosive to yellow metals and that they dont recommend it under any circumstance even if its "boiler plate" in nature they are still a corporation, profit-making and bottom-line driven and not likely receiving a lot of cool share-holder breezes up their skirt with 10% market share.

But I've seen enough endorsements from some other heavy-hitter sources that could easily be belived. However I must limit my influence in this matter to strictly API/Mobil Oil as far as the Mobil product is concerned.

But there's undoubtedly wriggle-room for both. The thing I take away from this is that the GL5 probably offers better built-in anti-friction protection. But that it "probably" has erosive elements that scare a manufacturer like Mobil enough to specifically recommend "against" its use and API to not endorse or label it as safe for yellow metal or synchro-mesh transmissions.

Hows a cocktail of 1Qt Mobil 1, 1Qt redline MTL 70W80 and 1Qt Redline MT-90 75W90 at every oil change sound ;-)

moribundman

I threw Mike's link in the oilheads' general direction. Let's see if they chew that bone.

JWG

140,000 miles on OEM fluid and about 50,000 on the older Amsoil 75w-90 gear oil. I had a German Tranny specialty shop in Oregon teardown and rebuild my tranny. The synchros after 50,000 miles on Amsoil showed no erosion. Older Amsoil was multi-rated, GL-4/GL-5 amongst many others. Amsoil used higher quality base stocks rather than a ****e-load of additives to achieve its multiple ratings. Despite some gear and slider damage (due likely to driver error: my missing a handful of shifts and my guests missing several shifts over nearly 200,000 miles), all the parts that came out of my tranny looked pretty good. Upon close examination, I could not tell why they replaced the synchros other than it is a softer metal and "consumable" tranny part compared to all the other parts.

My $0.02, look at the various new forumulations of Amsoil gear lubes; they may have something. Alternatively, have you looked into the Redline and/or Neo oil products? Also, high quality stuff as you yourself attest.

VAP

while "corporations" that make or rate the oils and spend trillions finding uses for their products conversely will not go that far out on a limb even if it means monumental sales increases. And ya gotta know those bastages want the money more than life itself.

Occam's Razor: The precept in modern philosophy stating: if all other things are equal the simplest explanation is always the correct one.

Whats the simplest explanation as to why Mobil/API wont endorse M1 or its GL spec in synchro-mesh transmissions? M1 isnt working off any "old wives tales" as they have gargantuan and sophisticated world-class laboratories. If their oil was safe and they were secure in selling it for GL4 specification applications why dont they? API is also a huge lab conglomerate. Why do they say GL5's should not be used in synchro-mesh trannies?

I have no answers but lordy lordy I have a lot of questions!!

MikTip

I re-read your email again....got it...

VAP

As far as I can tell M1 only makes one MT1 GL-5 product for use in transmissions and lists itself as "75W-90 Synthetic Gear lubricant" on the bottle.

The "e-monkey" could have misunderstood I guess but I dont know what product he could have confused it with from this question:

&lt;&lt;I need technical info regarding the potential long/short term negative affects, if any, of using MT1 GL-5 transmission oil in a manual transmission that specifies a GL-4 oil be used.&gt;&gt;

However its a small metter to run it by them again tomorrow, see what kind of answers we get next time.

MikTip

Right.... Whats in question here is M1. ;O)

MikTip

Basically buy a new/un-opened bottle of M1 &amp; Redline?

This way you eliminate the "in-use" factor.

Based on the results, maybe take it to the next level?