Mobil 1 for transmission?

[RichSD]

Help from experts needed.

I'm in the midst of a mild controversy on Miata net. Folk lore, some of which I've helped to propagate, holds that GL-5 synthetic lubes, Mobil 1 in particular, should not be used in manual transmissions with synchros.

Mobil's data sheet recommends against using in manual transmissions where GL 4 is required, presumably because of the high concentration of sulfur phosphate.

Miata recommends GL-4 or GL-5, without specification of additive type. The transmission indeed uses bronze/brass synchros.

Risk is easily avoided by using Redline MT 90 which is specifically formulated for manual transmissions. However, a lot of folks want to use Mobil 1 75-90 gear oil because of its ready availability, marginally lower cost.

What's the real scoop?? Do sulfur phosphate EP additives muck up yellow metals in transmissions? Are there other reasons not to use Mobil 1 in the transmission? Is this all a great marketing success by Redline?

Rich

 

[Spector]

Amsoil also makes a GL-4 lube in the weight you want however, of the two, I have had much better success with RedLine, worth the money. As to GL-5, I believe the answer to your question is yes and I would not take the chance, not worth it

 

[Al]

I agree with Spector. I believe I have read that the formulas of GL-5 will now be O.K., but I also wouldn't chance it. Go with the RedLine.

 

[BOBISTHEOILGUY]

I guess it's time to find some gl-4 and some gl-5 oils and do some analysis on them to see the ppm's on the ph and get a clarification as to if the newer gl-5's have that much more or equal ppms. Like in schaeffers case, with the use of moly then don't have to rely on the ph to get the barrier protection as much and that would account for some gl-5's capable of being used as a gl-4 replacement.

I don't have access to redline and if anyone does , if I could get a sample of it I'll send it in for a VOA. Same with a gl-4.

 

[Kevin in Texas]

quote:

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Originally posted by BOBISTHEOILGUY:
I guess it's time to find some gl-4 and some gl-5 oils and do some analysis on them to see the ppm's on the ph and get a clarification as to if the newer gl-5's have that much more or equal ppms. Like in schaeffers case, with the use of moly then don't have to rely on the ph to get the barrier protection as much and that would account for some gl-5's capable of being used as a gl-4 replacement.

I don't have access to redline and if anyone does , if I could get a sample of it I'll send it in for a VOA. Same with a gl-4.

---

Good idea Bob!

How about comparing a few syn, Pennzoil, Amsoil, and M1, to blends, Schaeffer & Valvoline, and dino's , Chevron Delo, Pennzoil.

I also think doing your backyard Timken test would give some interesting data along with the egg beater climbing oil test.

I am willing to send you some support $$ for materials.

 

[tgharch]

I have a 99 Mazda Protege ES. The Owner's Manual makes the same recommendation for the manual trans. lube as the Miata. I spoke with Mazda, they stated as long as it was a GL-5 lube it would meet the specs. When I asked them specifically about M1 lube. They gave me the standard answer about not commenting on any specific manufacturer.

This subject was a controversy on the Protege boards as well.

As for me, I have been running M1 for nearly 50,000 miles. Through normal use and some autocrossing, it has yet to cause a problem.

My father-in-law and my brother-in-law both run M1 in their transmissions.

 

[porterdog]

quote:

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Originally posted by BOBISTHEOILGUY:
I don't have access to redline and if anyone does , if I could get a sample of it I'll send it in for a VOA. Same with a gl-4.

---

About how much do you need? I have a small amount of MTL (GL4) and a GL5 rear end lube (75W90?) left from doing my car- happy to send them if they'll do...

Robert

 

[RichSD]

Ok, Let me see if I can refocus my question.

Specifically, do sulfur phosphor EP additives have an adverse effect on manual transmission brass/bronze synchros? If so, what is the effect?

I don't see how a timken test or other oil performance tests will address that issue. By definition, GL5 rated lubes perform better in extreme pressure applications than GL4 only lubes. The question is whether the claim (folklore) that the additional GL 5 EP additives corrode/damage/change or otherwise diddle the yellow metal components is true.

Rich

 

[Dick in Falls Church]

>>Specifically, do sulfur phosphor EP additives have an adverse effect on manual transmission brass/bronze synchros? If so, what is the effect?

OK, I'm not a tribologist and not a technician, but my understanding is that some of the sulfur compounds can become unstable and break apart should the gear lube become hotter than expected. The brass/bronze parts can then be attacked. Years ago, I recall seeing some really grungy yellow metal parts from VW manual transmissions--almost like an oxidation coating, which would flake off. This same material apparently plugged a small hole used to return slung lube back to the pan.

I also understand that some of todays GL5 lubes are suitable for GL4 use, because of the choice of extreme pressure additives which are more stable (or of different chemical properties).

 

[Bror Jace]

In addition to the interesting technical aspects of GL-4 and GL-5 gear oils, there was this original point of this thread which I feel the need to revisit for a moment:

"I'm in the midst of a mild controversy on Miata net. Folk lore, some of which I've helped to propagate, holds that GL-5 synthetic lubes, Mobil 1 in particular, should not be used in manual transmissions with synchros ... Miata recommends GL-4 or GL-5, without specification of additive type ... Risk is easily avoided by using Red Line MT 90 which is specifically formulated for manual transmissions. However, a lot of folks want to use Mobil 1 75-90 gear oil because of its ready availability, marginally lower cost."

Um, how much gear oil does an MX-5 Miata hold? 2 quarts? 3 quarts? A quart more than that?

OH MY GOD!

RichSD, maybe you can put this politely to your Mazda bretheren ... but I don't know if I could.

Buying new, they've spent $20,000+ on a high performace sports car. Is now the time to scrimp $3-9 on manual transmission oil changes which need to be done just every other year or so?

Get the proper Red Line, Schaeffer or Synergen gear oil ... COST NO OBJECT. The quantities involved are small and the drain interval is tens of thousands of miles.

Someone help me out here if I'm missing something.

--- Bror Jace

 

[porterdog]

quote:

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Originally posted by Bror Jace:
Someone help me out here if I'm missing something.

---

No, you got it right

Robert
1994 Miata, turbocharged to 220hp

 

[RichSD]

Bor and Porter,

Personally, I agree with your practical assessment, and have long adopted that route myself. I run Redline MT90 in the trans, and Mobil 1 in the diff. However, having perhaps more curiousity than good judgement, I'd like to understand the issue.

On the engine oil side, we spend a lot of effort/discussion to understand the science and applications to particular engines, stress levels. We discuss why TBN's important, shear stability, barrier additives..... in great detail and with significant information exchange. I was hoping that someone in the forum had some equivalant knowledge on the EP additive/yellow metal question. Some of the topics uncovered via "search" encouraged that hope.

Will the answer change my use of lubes? No, as noted above, I've picked a "sure safe" solution. But, curiousity rules and, if I'm passing an opinion or recommendation on to someone else, I prefer to understand the fundamentals behind that recommendation. If no one has better info, ok fine. Life goes on and MY trans is well protected.

Thanks for the replies,

Rich

 

[Bror Jace]

RichSD, I like you, would like to know the real deal behind GL-4 vs. GL-5 and the corrosion issue. My guess is that GL-5s were all originally formulated with sulfur EP compounds which were corrosive to certain metals such as brass and bronze (copper and various amounts of tin). As I understand it, if you leave sulfur compounds in an environment which will eventually collect moisture, you’ll eventually get sulfuric acid and be giving your gears a bath or oil mixed with “acid rain.” I know this is an (over)simplified layman’s explanation and the chemists in here are free to correct anything and everything I said.

So, I suspect that many companies have/are transitioning away from those sulfuric compounds in their GL-5 oil (to moly and maybe others) so some of those formulations are probably safe. BUT, if I were writing an equipment/vehicle owner’s manual, I’d specifically tell people to stay away from GL-5 gear oils until I was pretty sure that corrosive ones on the market were an extreme rarity. I don’t think that’s the case ... not yet, anyways.

Anyway, you say you are still using Mobil 1 in your rear end. Any particular reason?

You’ve obviously secured a source of Red Line. Why wouldn’t switch all your gear oils over to the super-premium stuff?

--- Bror Jace

 

[RichSD]

Hi Bror,

Actually, I'll do that next changeout. I used Mobil 1 primarily because I was out of Redline, had some time free one Saturday, Mobil 1 is allegedly a quite good GL-5 lube and it's available almost anywhere. It's certainly a step up from the dino juice that's OEM.

It seems that we've both read the same or similar sources and followed the same logic concerning sulfur additives and interaction with yellow metal alloys. I would like to hear from someone with real metalurgy or tribo credentials confirm that view. I could dig into the SAE literature, but my affiliation's IEEE so don't have ready access or know the efficient search routes. Plus, I'd be reading with a technically literate, but outside view. Drawing quick conclusions without context can lead to a major bite in the butt. Been there, done that, will probably do again!

Rich

 

[Bror Jace]

Rich, good luck with the Red Line. Just to makes things even more confusing, Synergen makes a "GL-6" gear oil: their "Syngear II Racing", which I have heard guys rave about. I'm talking Toyota Atlantic racers as well as vintage racers (not truckers and weekend warriors with their hot-rodded roto-tillers). Of course, Synergen is probably even harder to source than Red Line.

Also, I did a quick 'net search and most GL-5 gear lubes still use sulfur phosphorus so my comment above that many may be phasing this stuff out was, at the very least, premature.

you said: "I would like to hear from someone with real metalurgy or tribo credentials ..."

Yep, me too. However, in the meantime, I feel the need to investigate things as best I can.

I found this on Chevron's site:

"The sulfur-phosphorus extreme pressure additives in Chevron RPM Universal Gear Lubricants reduce the spalling and wear of gears by creating a microthin sacrificial film on the surface of the gear teeth which is actually softer than the gears themselves. Frictional heat and pressures between tooth surfaces cause the sulfur-phosphorus to react with the surface of the gear teeth at the point of contact, thus creating the sacrificial film."

I bolded those sections. It would appear that the "reactive" nature of the GL-5's critical ingredient is alive and well. Brass/bronze components beware!

--- Bror Jace

 

[Pablo]

I think this GL-5 and synthetic "fear" comes not so much from the antiwear additives, as it does from a fear of the lube being too "slippery" for the synchromechanisms to do their job.

A TRULY UNBIASED, SCIENTIFIC GEAR LUBE SHOOTOUT WOULD BE GREAT!!!!!!!

I do use (as do many others) Amsoil Series 2000 gear lubes in MT's that may call for GL-5 or MT(Toyota, Volvo (M47) and domestic) with zero problems - this stuff is GL-2 - GL-5 and MT-1 rated - I'm not sure why it's so readily scoffed at here.

[ November 03, 2002, 08:53 AM: Message edited by: Pablo ]

 

[Bror Jace]

Pablo said: "I think this GL-5 and synthetic "fear" comes ... from a fear of the lube being too "slippery" for the synchromechanisms to do their job."

I don't see anyone here making that sort of statement.

If you look at the statement I lifted off of Chevron's site, it talks about the (chemical) reactive nature of the sulfur phosphorus. Corrosion is a chemical reaction and Chevron's statement plays right into the fears we have held since trying to choose between the two classes of oils for synchromesh transmissions.

I'm gonna bring up the other GL-5 thread in this forum and see what widman, a foreign Chevron rep, says about the different gear oils.

--- Bror Jace

 

[sprintman]

Bror
Would you call Redline 75W90NS GL5 a corrosive oil? If yes is there a suitable Redline or say Mobil product for my Sube Outback which specifies a GL5?
tks..s

 

[Pablo]

To Bror, I should have been more clear: some fear comes from the Redline gear lube bottle, for example, about synthetic GL-5 and synchros in transmissions (not this EXCELLENT site)

 

[Bror Jace]

Pablo, no problem.

sprintman, I have only used their MTL (70W90?) in my Honda synchromesh transmissions and have not researched their other gear oils for different applications.

I know a buddy who has another buddy who's buying one of their heavier weights for his old Land Rover because of corrosive fear with other GL-5s.

You could e-mail Red Line with your application (include as many specifics as possible) and Dave Granquist or someone else will get back to you with a recommendation.

--- Bror Jace