Transmission / Diffy Oil, redux...

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acarlson
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Transmission / Diffy Oil, redux...

Post by acarlson »

A member on the other forum posted an update to his white paper on what's good & what's bad regarding transmission and differential oil.

I thought the members here might like to read up on that: http://corvaircenter.com/phorum/read.php?1,1073996

Alec
Alec Carlson
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Re: Transmission / Diffy Oil, redux...

Post by bbodie52 »

I have tried to follow Richard Widman's excellent research on oil products for years, and his latest paper (attached) is very informative. However, it does not really include any comments on the Royal Purple gear lube product, which seems to fit many of his desirable criteria for the Corvair transaxle. For your consideration, here is some of the information provided by Royal Purple...
Overview

Royal Purple Max Gear is recommended for use in truck and automotive front or rear differentials, manual transmissions and lower gear units of marine engines that specify use of an API GL-5 or GL-4 fluid. It is non-corrosive to soft yellow metals (brass, bronze, copper, etc.) and synchronizer safe. Specially designed to extend gear and bearing life, Max Gear provides superior corrosion protection over competing conventional and synthetic gear oils. Royal Purple engineered this ultra-tough, high-performance automotive hypoid gear oil to provide maximum protection to heavily loaded gears while maximizing power throughout the drive train. Max Gear outperforms ordinary gear oils by combining the highest quality synthetic oils with Royal Purple's proprietary Synerlec additive technology. Max Gear makes gears run smoother, quieter, cooler and longer without overhauls. A direct reduction of drag in the drive train has huge advantage for trucks and other 4-wheel drive vehicles: better gas mileage. Max Gear is formulated with a friction modifier additive - no additional additives are necessary.
bbodie52 wrote:I would never take the risk of loading GL-5 gear oil into any manual transmission, or into a Corvair transaxle, which does not isolate the differential gear oil from the transmission section. Why would you want to take the risk of damaging your Corvair transmission? GL-5 gear lubricant is fine in a Corvair differential that is part of a Powerglide transaxle, since the automatic transmission is isolated from the differential gear lubricant. But manual transmission transaxles should only use GL-4 gear lube, or the GL-4/GL-5 rated synthetic like the Royal Purple Max Gear synthetic that is specifically formulated to be fully compatible with manual transmissions and the "yellow metals" they contain.
MAX GEAR – HIGH PERFORMANCE SYNTHETIC GEAR OIL
Max Gear – High Performance Synthetic Gear Oil
Max Gear is recommended for use in truck and automotive front or rear differentials, manual transmissions and lower gear units of marine engines that specify use of an API GL-5 or GL-4 fluid. It is non-corrosive to soft yellow metals (brass, bronze, copper, etc.) and synchronizer safe. Specially designed to extend gear and bearing life, Max Gear provides superior corrosion protection over competing conventional and synthetic gear oils.

We engineered this ultra-tough, high performance automotive hypoid gear oil to provide maximum protection to heavily loaded gears while maximizing power throughout the drive train. Max Gear outperforms ordinary gear oils by combining the highest quality synthetic oils with Royal Purple’s proprietary Synerlec® additive technology.

Max Gear makes gears run smoother, quieter, cooler and longer without overhauls. A direct reduction of drag in the drive train has huge advantage for trucks and other 4-wheel drive vehicles: better gas mileage. Max Gear is formulated with a friction modifier additive – no additional additives are necessary.



Max Gear is available in the following viscosities: 75W-90, 75W-140, 80W-90, 85W-140 and SAE 90

All Max-Gear oils contain limited-slip friction modifier. Max Gear oils contain the limited-slip friction modifier necessary for proper function of limited-slip differentials. There is no need or benefit to adding additional limited-slip friction modifier


Please email rpautotech@royalpurple.com. Our experts can answer any questions you may have.

For further information or questions please contact Royal Purple technical support directly by email or by phone.
http://www.royalpurpleconsumer.com/contact/
Phone: 281-354-8600
Toll Free: 888-382-6300
Attachments
The Difference between GL-4 and GL-5 Gear Oils - Richard Widman (Revision 5-2020a).pdf
The Difference between GL-4 and GL-5 Gear Oils - Richard Widman (Revision 5-2020a)
(871.64 KiB) Downloaded 20 times
Selection of the Right Motor Oil for the Corvair and other Engines - Richard Widman.pdf
Selection of the Right Motor Oil for the Corvair and other Engines - Richard Widman
(2.38 MiB) Downloaded 21 times
Brad Bodie
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Re: Transmission / Diffy Oil, redux...

Post by bbodie52 »

From: Richard Widman <rwidman@gmail.com>
Sent: Saturday, May 02, 2020 10:06 AM
To: Brad Bodie <bodiefamily@msn.com>

Subject: Re: Royal Purple MaxGear 75W-90 for Corvairs

They are not very clear in any of their documents, so I have written, and will let you know if their answer confirms or not.
_____________________________
Richard L. Widman | CEO
(591-3) 344-2233 / (591-7) 705-2487
www.widman.biz
Widman International S.R.L.
Carretera al Norte km 6
Santa Cruz de la Sierra - Bolivia


On May 1, 2020, at 8:07 PM, Brad Bodie <bodiefamily@msn.com> wrote:

I really enjoyed your recent update on gear lube properties and applicability for use in the Corvair transaxle. Their Max Gear Synthetic 75W-90 would appear to meet many of the criteria you would find desirable for the Corvair transaxle. While it is listed for both GL-4 and GL-5 applications and their marketing states it has properties making it a good product for hypoid gear differentials and manual synchronized transmissions, I still am not certain as to how it would measure up to your standards. I do a lot of writing on the Corvair Forum, and your updated paper has again made this a topic of conversation. Have you had a chance to consider the Royal Purple product? What is your opinion of it for use in Corvair manual transaxles?

RE: viewtopic.php?f=55&t=16077

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Re: Transmission / Diffy Oil, redux...

Post by bbodie52 »

From: Richard Widman <rwidman@gmail.com>
Sent: Saturday, May 02, 2020 2:29 PM
To: Brad Bodie <bodiefamily@msn.com>
Subject: Re: Royal Purple MaxGear 75W-90 for Corvairs

Probably won’t get an answer til Monday, but the more I read of their product sheets, the more I think the Max Gear is wrong for out cars. The MT line of products specifically says it is for synchronized manual transmissions, whereas the Max Gear only says synchronizer safe after describing the EP package without detail.
_____________________________
Richard L. Widman | CEO
(591-3) 344-2233 / (591-7) 705-2487
www.widman.biz
Widman International S.R.L.
Carretera al Norte km 6
Santa Cruz de la Sierra - Bolivia
Brad Bodie
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Re: Transmission / Diffy Oil, redux...

Post by Richard1 »

To finish this off, here was my response to Brad

"They answered my email, and based on that I recommend against Max Gear.

They say their formulas are proprietary, and they mention the synchronizers in relation to the non-corrosive formula. So it is basically a standard sulfur/phos EP, fine for differentials"
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