Who's using RLI 75W-90 in their manual gearboxes?

[Yuk]

I was sure I was going to buy Amsoil a few months back, but had to wait because of other pressing financial issues. Now I think I'm on the verge of buying 4 gallons of the RLI stuff, any user feed back?

Thanks.

 

[Yuk]

OOPs! Would the Mods please move this? I put it in the wrong forum. I meant to put it in the ATF, Differential, Trans, Brake, P/S section.

Thanks

 

[Johnny]

Yuk, I requested the mods move this for you. In the future if you want to ask them to do this, just click on notify in the bottom right of your post and you can make the request.

 

[Yuk]

Thanks Johnny.

 

[KC Strip]

My gearbox isn't manual, but so far I like the RLI stuff.

 

[MolaKule]

Why would you want to use a differential fluid in a manual transmission?

What is you vehicle?

 

[SubLGT]

I'm using it in the rear diff of my Subaru.

 

[cos]

Ya, why use a diff fluid in a trans?

 

[Yuk]

Originally Posted By: MolaKule
Why would you want to use a differential fluid in a manual transmission?

What is you vehicle?


Huh???

I don't want to use differential fluid in my manual transmissions. I want to use transmission fluid that will be compatible with the 5 speeds in my Mazda 6, VW Passat and Nissan Sentra. When I asked Terry Dyson, via email, what he recommended for my multi-car application he recommended RLI Bio-Synthetic 75W90 GL-5 LS. Which according to the RLI website:
..." is designed to meet the SAE J306 requirements for manual transmissions, differentials (including limited slip (LS) units), and transfer cases."

What makes you think RLI Bio-Synthetic 75W90 GL-5 LS is not compatible with manual transmissions?

 

[INDYMAC]

Because GL4 is normally recommended by manufacturers for manual transmissions. They do not contain additives that are harmful to yellow metals like the brass in the synchro's. GL5 does contain additives that are harmful to yellow metals. Yellow metals are not normally used in differential final drive gears and LSD's. If RLI does in fact state that their gear oil is GL4/GL5 and compatible with all manual transmission applications (does not contain harmful additives), then I would think it is good to go. Maybe a phone call to RLI would help to make sure. Good luck.

 

[Yuk]

Originally Posted By: INDYMAC
Because GL4 is normally recommended by manufacturers for manual transmissions. They do not contain additives that are harmful to yellow metals like the brass in the synchro's. GL5 does contain additives that are harmful to yellow metals. Yellow metals are not normally used in differential final drive gears and LSD's. If RLI does in fact state that their gear oil is GL4/GL5 and compatible with all manual transmission applications (does not contain harmful additives), then I would think it is good to go. Maybe a phone call to RLI would help to make sure. Good luck.


The Mazda and the Nissan both call for either GL4 or GL5. The 1999 vintage VW specified GL4. Terry Dyson said, " The concern from 1999 about GL4 is no longer a serious issue for a well formulated GL5, especially synthetic."

I imagine that he is qualified to make this statement. If anyone disagrees, particularly Molakule, I'd love to hear their reasoning.

 

[SubLGT]

What will be a typical daytime temperature during winter in Edmonton?

 

[bulwnkl]

I use RLI's 75W90 in my front and rear diffs. I've contemplated putting it in my Mazda's transaxle, but probably won't. There's not a 'compatibility' problem, but I have found that in many cases a manual transmission fluid will allow better shifting than a differential fluid like the RLI. Not always, but in many cases.

 

[Yuk]

Originally Posted By: SubLGT
What will be a typical daytime temperature during winter in Edmonton?


Daily Average Temperature:

Jan -11.7°C
Feb -8.4°C
Mar -2.6°C
Nov -4.1°C
Dec -9.6°C

Of greater concern to Edmontonians is the fact that we frequently see overnight temperatures below -25°C. At that temp I often need two hands to get the Sentra into gear, and shifting doesn't really begin to lighten up until about 10 minutes into the journey.

 

[SubLGT]

At those temperatures you might be more satisfied with one of the lower viscosity GL4 transmission oils from Amsoil or Redline

 

[SubLGT]

In my Subaru trans, I am using a GL4/GL5 75W90 gear oil from Specialty Formulations, called MTL-R.

MTL-R has a viscosity of 14.7 cSt at 100degC, and for comparison their HDS-S 75W90 rear end lube has a viscosity of 18.0. The BioSyn 75W90 has a viscosity of 15.7. The MTL-R is working well for me at 20 degF.

Other viscosity numbers (from 2005 data sheets):
Pennzoil Synthetic 75W90 GL4 is 15.3 cSt
Pennzoil Synthetic 75W90 GL5 is 15.7 cSt
Castrol HypoyC 75W90 GL5 is 15.7 cST
Castrol Syntec 75W90 GL5 is 15.0 cST
Mobil1 75W90 is 15.2 cST
Valvoline Synpower 75W90 is 14.9 cSt.

 

[MolaKule]

I generally, as a matter of principle, do not suggest differential lubricants in manual transmissions for two primary reasons: improper viscosity and lack of proper friction modifier.

The viscosities of differential lubricants for 75W90 viscosites is at least 3 cSt higher than manual transmission specific lubricants in 75W90. The mt area most affected by too thick a viscosity is the shifter fork and sliding gear sets and usually prevents smooth downshifts in cold weather.

In addition, the friction modifiers for mt's and diffys are not the same.

https://bobistheoilguy.com/forums/threads/synchromesh-manual-transmission-lubricants.93561/

(BTW, the mods were supposed to delete the first posting and keep the latter).

Quote:
SAE J306 requirements for manual transmissions


This statement by SAE usually referes to heavy duty truck transmissions or MT-1 specs, not light truck and automotive manual transmissions.

 

[digitalSniperX1]

In some cases where GL-5 was spec'd for manual transmissions, the manufacturer later changed back to GL-4. I know this is the case for the Mazda RX-8 transmission. GL-5 in them were ruining the synchros.

I do not know if ALL GL-5's are detrimental to manuals specifying GL-4's. I just know that some GL-5's were ruining RX-8 trannies and the spec was modified as a result. Of course the original spec may've simply been a typo in their service/owner's manuals.

 

[Yuk]

Thanks Mola. Looks like I have some reading in my future.

 

[tdi-rick]

Originally Posted By: digitalSniperX1
In some cases where GL-5 was spec'd for manual transmissions, the manufacturer later changed back to GL-4. I know this is the case for the Mazda RX-8 transmission. GL-5 in them were ruining the synchros.

I do not know if ALL GL-5's are detrimental to manuals specifying GL-4's. I just know that some GL-5's were ruining RX-8 trannies and the spec was modified as a result. Of course the original spec may've simply been a typo in their service/owner's manuals.


Do some reading in the tech articles section, as this comes up far too frequently. Molakule has written some very good papers on EP adds in GL5's.

Quickly, anything that is dual rated is safe for yellow metals.
If in doubt, look for the copper corrosion test results in the PDS. Anything with 1a or 1b is ok.
Even most straight GL5's these days use buffered sulphur compounds which are non reactive.