Synchromesh in GL-4 Transmisson?

[Jelly]

I can't find help anywhere else, so hopefully someone here will have an idea. I have a NV4500 transmission that calls for a 75w or 80w-90 GL-4 lubricant. As far as I know, the NV4500 needs a GL-4 lube for a few reasons: At high temperatures, phosphorous plates out and reduces the coefficient of friction of the synchronizer rings. Since there is twice the amount of sulfur/phosphorous in GL-5 lubes, there is a higher detrimental effect. Also, the same additive package can attack "light" metals at higher temperatures. Why would Pennzoil Synchromesh not be good in this application? Synchromesh: http://www.pzlqs.com/Tech/Pdsheet/DomesticMarketing/Gear&Transmission/pdf/SynchromeshFluid.PDF GL-4's: http://www.pzlqs.com/Tech/Pdsheet/DomesticMarketing/Gear&Transmission/pdf/GearplusSAE80W90GL-4.PDF http://www.pzlqs.com/Tech/Pdsheet/DomesticMarketing/Gear&Transmission/pdf/SyntheticSAE75W90GL-4.PDF http://www.pzlqs.com/Tech/Pdsheet/QuakerState/Gear&Transmission/pdf/MultiPurposeGL-4GearLubricants.PDF Seems the main difference is that the Synchromesh is thinner... Thanks for any help guys. [ October 12, 2004, 03:43 PM: Message edited by: Jelly ]

 

[Michael SR]

is your tranny the one that comes with syntorq as factory fill? synchromesh isn't actually GL-4 rated, but you knew that. it seems to be specified and used in cases where an ATF or engine oil have typically been used. i personally would worry a bit about using it an application that specifically asks for GL-4. besides being thinner, i can't get over the possibility that it doesn't have a GL-4 rating because it wouldn't be able to pass the tests (as opposed to them just not bothering with certifying it). why not syntorq? -michael

 

[Jelly]

quote:

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Originally posted by Michael SR: is your tranny the one that comes with syntorq as factory fill? why not syntorq?

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Yes...because it'll cost me $100 to fill my transmission, and even when I got it (filled with "proper" expensive lubricant), shifting was subpar, so I've been wanting to try some different lubes to see if shifting improved at all.

 

[MolaKule]

quote:

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At high temperatures, phosphorous plates out and reduces the coefficient of friction of the synchronizer rings. Since there is twice the amount of sulfur/phosphorous in GL-5 lubes, there is a higher detrimental effect. Also, the same additive package can attack "light" metals at higher temperatures.

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1. The main EP package in gear lube is composed of a Sulfur-Phosphorus package with secondary EP/AW containing Boron and other schtuff! See this thread: http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=4;t=000226#000000 In that thread, you will see that extra additives are there to protect against Yellow-Metal staining and metal corrosion. 2. Phosphorus doesn't plate out, but is in there to protect against high loading pressures and to prevent galling. Some phosphorus compounds also acts as friction reducers. If the tranny specification calls for a 70-90 weight oil, then any of the PZ or QS oils should suffice. I would however pick the one with the lowest viscosity. And yes, the only difference between the GL-4 70-90's and the Synchromesh (9.5 cSt) is the 100 C viscosity. The additive packs are almost identical.

 

[Jelly]

Thank you Michael and Mola for the replies. Mola - Thank you for the link!

 

[Michael SR]

quote:

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Originally posted by MolaKule: And yes, the only difference between the GL-4 70-90's and the Synchromesh (9.5 cSt) is the 100 C viscosity. The additive packs are almost identical.

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wow, really? i wonder they don't just label it GL-4, then. is it the worry that people will try to use it where a 90 weight is called for, just because they see the "GL-4?" or is it a cost thing? -michael

 

[MolaKule]

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And yes, the only difference between the GL-4 70-90's and the Synchromesh (9.5 cSt) is the 100 C viscosity. The additive packs are almost identical.

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Just wanted to add one more item: And yes, the MAJOR difference between the GL-4 70-90's and the Synchromesh (9.5 cSt) is the 100 C viscosity. The additive packs are almost identical. The MINOR differences are the Friction Modifiers. The synchromesh-type fluids have a special friction modifier component that the 70-90's don't have. GL-4 and 5 gear lubes for 70-90 weight are speced to have a minimum visocsity > 9.8 cSt. Synchromesh fluids may vary between 7.5 and 9.5 cSt. The GL-4 EP additive pack has 30-60% of the GL-5 EP additive pack.