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Discussion Starter · #1 ·
everywhere I read people say not to use GL-5 manual transmission oil as it contains sulfur and will eat your brass synchros.... so why does the manual state that it's ok to use GL-5 oil?! To be precise, it states "API Service GL-4 or GL-5 SAE 75W-90"

Is this some kind of an out of control fairy tale?
 

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The Full Dong
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Trust me. It is no fairy tale, as I am now paying the price for using some cheapo GL5 gearoil for a few a while. All gearbox oils are not created equally and thus have verying amounts of sulfer in them. Some more then others. You can probably find some GL5 with a low amount of it and be fine.
 

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El Pepe said:
everywhere I read people say not to use GL-5 manual transmission oil as it contains sulfur and will eat your brass synchros.... so why does the manual state that it's ok to use GL-5 oil?! To be precise, it states "API Service GL-4 or GL-5 SAE 75W-90"

Is this some kind of an out of control fairy tale?
GL5 is a more stringent standard than GL4. Thus, the manufacturers have to use more EP (extreme pressure) additives, many of which (including the sulfurous ones) are corrosive to brass parts in the transmission.

Here is a description from a tribologist (lubrication scientist):
"GL-4; Specified for hypoid gear service under severe service but without shock loading. This classification is essentially obsolete but is still specified by some manual transmission/transaxle manufacturers. Implies an EP/AW additive package that contains 30% to 50% less S-P additives than the GL-5 service classification. Some Marine Gear Lubes fall into this classification, especially the full Synthetic Marine Gear lubes and specialty blenders MT lubes that use high levels of esters.

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. "

Source: http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=4;t=000225

Note that "most gl-5 lubes contain metal deactivators that prevent attacks by the EP additives." This shouldmean they are reverse compatible with the GL-4 lubes, but in reality YMMV. I personally only use the Redline MT-90 GL4 fluid.

The Redline fluid has a largely Ester base, doesn't have the level of EP additives that are in GL4, and manual transmissions almost universally love the stuff.

Anyhow, GL5 doesn't require the nonferrous metal protection, so whether or not the manufacturers implement it is up to you to guess. The only way to find out for sure would be an expensive (500 dollar) GC/MS test and interpretation. Its your transmission.

The Redline MT-90 is proven, we know it doesn't eat brass parts, and it shifts better than anything else.

Thanks for asking this though, its a great question.
-Garrett
 

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Discussion Starter · #4 ·
Radar said:
Trust me. It is no fairy tale, as I am now paying the price for using some cheapo GL5 gearoil for a few a while. All gearbox oils are not created equally and thus have verying amounts of sulfer in them. Some more then others. You can probably find some GL5 with a low amount of it and be fine.
well, how can you be certain that your troubles are caused by the GL-5 oil, and that they would not have happened anyways if you continued to use GL-4? Did you take your gearbox apart to examine the brass parts?
 

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Discussion Starter · #5 · (Edited)
Re: Re: Why is GL-5 BAD?!?

skiingman said:
GL5 is a more stringent standard than GL4. Thus, the manufacturers have to use more

...

The Redline MT-90 is proven, we know it doesn't eat brass parts, and it shifts better than anything else.

Thanks for asking this though, its a great question.
-Garrett
thanx for the detailed info Garrett! appreciate it. But I'm still not super convinced.... I have not heard of ANY cases of confirmed synchro corrosion due to GL-5 oils. If anybody claims so, I want to see the pictures. What I read somewhere is that the GL-5 oils might STAIN the yellow metals, but not much more than that.... I'm probably gonna go with redline as well, but I don't think GL-5 manufacturers would open themselves up to the potential lawsuits by producing "corrosive" gear oils....
 

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The Full Dong
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This is striaght from Julians site (http://homepage.ntlworld.com/dorothy.bradbury/probemx/)


"The correct all-temperature gearbox oil weight is 75w90. A GL-5 oil can only be used if it does not contain sulphur. Only one GL-5 oil in the UK at the time of writing does not contain sulphur, thus it is best to telephone the manufacturer of the oil using the number of the reverse of the bottle. The use of a gearbox oil which does contain sulphur will halve the life of the synchros & bearings as they are of a bronze/brass construction. The reason is that sulphur (eg, manganese sulphonate) becomes acidic. Hence, Mobil1 75w90 GL-5 is NOT suitable for Mazda gearboxes as Mobil confirm.

Notchy shifting is common place during cold mornings and can be corrected by changing the oil to Full Synthetic Redline MT90 75w90 GL-4.
Notchiness is due to synchros requiring an opposing viscosity of oil to differentials, yet both must share the same oil. Thus manual gearbox oil must not only cover both synchro & differential requirements, but do so over all encountered operating temperatures. Non-synthetic oil cold weather viscosity prevents synchros operating properly. Some manuals list ATF as an appropriate oil - this is incorrect. Engineering tolerances for ATF v 75w90 gearbox design differ.
A synthetic gear oil provides better gear-teeth protection & lubrication, reduces transmission losses during warmup so aiding the environment regarding emissions & fuel usage.

Some notchy shifting may be due to a non-disengaging clutch, either through wear or use of non-OEM parts (eg, ACT which require adjustment). "
 

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Discussion Starter · #7 · (Edited)
Radar said:
This is striaght from Julians site (http://homepage.ntlworld.com/dorothy.bradbury/probemx/)

...

Some notchy shifting may be due to a non-disengaging clutch, either through wear or use of non-OEM parts (eg, ACT which require adjustment). "
Well, you guys raised enough doubt in my mind to use GL-4 fluids, but possibly out of all the FUD around this topic and not due to reasonable reasons. Maybe RedLine's marketing department had something to do with that fuddddddd.....

When I go to Mobil1 site the only documents about Mazda refer to ATF type F fluid

When I look at the features of Mobil 1 Synthetic Gear Lubricant LS 75W-90, I see this as one of them: "Excellent rust, staining and corrosion protection of copper and its alloys"

here is another GL-5 oil that contains sulphur and is safe with brass

http://www.imperialoil.ca/Canada-English/Files/Products_Lubes/IOCAENCVLESEsso_GO_LS80w90.pdf

Lastly, wouldn't have mazda have put a warning beside the GL-5 specification in the manual if there was a possibility of using corrosive ones?
 

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El Pepe said:


Lastly, wouldn't have mazda have put a warning beside the GL-5 specification in the manual if there was a possibility of using corrosive ones?
No. Why should they care? Mazda never mentions stuff like that in the manual. Toyota does however, I read a Corolla manual the other day and was amazed at all the common-knowledge stuff they included. Very helpful.
-Garrett
 

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Discussion Starter · #9 ·
skiingman said:
No. Why should they care? Mazda never mentions stuff like that in the manual. Toyota does however, I read a Corolla manual the other day and was amazed at all the common-knowledge stuff they included. Very helpful.
-Garrett
why should they care? well, cause if people were putting GL-5 into their trannies during the warranty period, and IF it was eating their trannies then obviously that would make them care....
 

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Discussion Starter · #10 · (Edited)
just FYI... a typically cautious reply from Mazda USA:

Thank you for contacting Mazda North American Operations. I appreciate
the opportunity to respond to you.

In regards to your question, Mazda has tested the GL-4 and GL-5 and has
determined this is safe and effective for the Mazda 626. Mazda does
not recommend adding any synthetic products to the Mazda vehicles
because Mazda has not tested them and has no way to know if they are
safe. Please understand I'm not technically trained and therefore not
in a position to go into more detail on your questions. You may want
to contact the Service Department at your local Mazda dealership if you
want a more detailed answer on why Mazda recommends this particular
transmission fluid as they are technically trained by Mazda and may be
able to answer your questions.

Again, thank you for contacting Mazda. It has been my pleasure to
assist you. Please feel free to reply to this message with any further
questions or comments.

Please take a moment to give us your opinion about our e-mail service.
Click the link below to complete a brief, online survey.

http://www.....

Regards,

Heather Drake
Specialist, Customer Assistance E-Business
---
what I dont' understand is why don't they ASK someone "technically trained"... if they don't know the answer.... You'd figure a car company would be able to find couple of "technical" people, no?
 

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El Pepe said:
what I dont' understand is why don't they ASK someone "technically trained"... if they don't know the answer.... You'd figure a car company would be able to find couple of "technical" people, no? [/B]
Pssssht. When was the last time you were at your local Maz-duh dealership. I am convinced that no one who works there is technically trained. :E
 

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Re: Re: Why is GL-5 BAD?!?

skiingman said:
tribologist (lubrication scientist)
i coulda used one of those last night :\
 

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Thereal ZEscort said:
Pssssht. When was the last time you were at your local Maz-duh dealership. I am convinced that no one who works there is technically trained. :E
Quite true. I had the head of my local Mazda parts department swear up and down at me that my MX6 LS did not have VRIS, and that only the RX7s had it. So, when I asked him to come outside and tell me what those two solenoids in the IM are for, would you believe he told me they were EGR valves? Of course, when I asked him why my car would need 2 EGR valves, he had no answer.

And this was the guy who had his name all over the parts department wall for certifications and such... pretty pathetic.
 

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Discussion Starter · #14 ·
Thereal ZEscort said:
Pssssht. When was the last time you were at your local Maz-duh dealership. I am convinced that no one who works there is technically trained. :E
I guess it's the roll of the dice... I'm actually pretty happy with the knowledge of the mazda people I have dealt with in Kramer mazda in Calgary.... not too happy about their prices though...
 

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I thought I'd mention this quickly ... as I don't really have time to read the whole thread to find out whether it has been mentioned.


All Gear oils contain some sulpher. GL4 contains less than GL5. However, if you get a multi-rating gear oil ... GL4 contains non-ferrous metal protection which preserves our synchros but doesn't protect the main gears, ... however GL5 is more robust and will decrease wear and tear on the main components in the gear box and increases wear on non-ferrous metal parts.

Thus ... I'm deducing that a GL4/5 rating (ie. Motul Gear 300) will be ideal ... however a GL5 (ie. Castrol Syntrax) wouldn't be any good for us. Straight GL4 is very hard to come by in Synthetic form. Yes, redline has a product that is, and it apparently performs well, however I've heard that it breaks down quicker than Mineral Gearbox Oil.

Cheers,

Nath
 

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i put crappy gl5 gear oil in a few months ago, my 3rd gear grinds pretty bad now, i think it did a little before but not as much. on the way i have sime BG syncroshift, its supposed to be far better than redline from what ive read.
 
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