Standard oil with Gripper?

[scullyg40]

I've read a couple of threads on here regarding the best oil for a Gripper'd box, and the one most recommended I believe is Redline MT90 75W90 GL4.

I've found a pdf from Gripper which says to first follow the recommended oil. It also says it can cope with anything, even engine oil or just CV grease.

https://gripperlsd.com/wp-content/uploads/2017/08/GRIPPER-LSD-OIL.pdf

Which got me thinking. What's the reason for upgrading to Redline MT90 or similar. Is it just heat that the standard gearbox oil (Elf 75W80) can't cope with? What happens with the oil if it get's to hot? If heat is the issue, would cooling be an answer to be able to use the Elf 75W80?

Reason for asking, is that the Redline is quite a bit more expensive than the Elf oil, and with more frequent changes because of the Gripper, it can soon ad up.

Also, would Motul 75W90 LS 300 be just as suitable as Redline MT90? It seems to be a bit more available where I live and for a slightly better price.

 

[imprezaworks]

@NorthloopCup

 

[NorthloopCup]

If you put the oil in that gripper recommend you’ll kill the synchros. That is as guaranteed as day turns to night, and night turns to day.

Redline mtl, or mt90.

Ultimately mate, you run whatever oil you want in the box. The main reason for my sway towards redline is because of the oil spec. Jc5’s don’t need a GL5 oil as it’s too slippery and kills synchros.

 

[JamesBryan]

Run the oil for the box not the diff basically.

 

[oilman]

As the poster above, stick with what the gearbox wants. With the addition of the lsd just change more regularly. The Elf 75w-80 will cope, just the Redline is the next level up so can cope better.

Cheers,

Guy.

 

[scullyg40]

Thanks for the replies. Choosing oil for the box and not the diff is what I've read before, likewise for gl4 for the brass synchros.
So apparantly using the standard oil is fine as long as you change regularly?
@NorthloopCup Can you share a bit about which specs you mean? Beyond hot and cold viscosity, my oil knowledge is gone. 😁

 

[oilman]

He is talking about the difference between API GL4 and API GL5. These are the common universal specs for gear/diff oils. Once upon a time they used different additives and the API GL5 could attack yellow metals in the synchromesh. So it was API GL4 for synchromesh gearboxes and API GL5 for differentials. That is still a good rule of thumb to follow in many cases, the extreme pressure additives used these days are same in both API GL4 and API GL5 so there is no worry of GL5 attacking yellow metals anymore. However, API GL5 has about twice as much of the EP additive as a API GL4 and this is what causes the oil to be too slippy for some gearboxes such as the jc5, this leads to the grinding of gears and eventually killing the synchros.

Stick to an API GL4 spec oil and all will be fine.

Cheers,

Guy.

 

[scullyg40]

@oilman Thanks, that's a really good explanation about gl4 and gl5.
But the Elf 75W80 and Redline MT90 75W90 are both gl4, so @NorthloopCup must mean something else?
I thought the Motul 75W90 LS 300 was gl4 as well, but apparantly it's gl5.

 

[NorthloopCup]

I personally wouldn’t put elf oil in the box as it won’t stand the temps a plate diff will generate.

 

[oilman]

@oilman Thanks, that's a really good explanation about gl4 and gl5.
But the Elf 75W80 and Redline MT90 75W90 are both gl4, so @NorthloopCup must mean something else?
I thought the Motul 75W90 LS 300 was gl4 as well, but apparantly it's gl5.

The Motul Gear300 LS is a 75w-90 and API GL5, ideally you want a 75w-80 API GL4 which is why the Redline MTL is so popular. If you wanted to look at the Motul then the normal gear300 75w-90 would be the one to go for as it meets both GL4 and GL5 (essentially a GL4 oil that also passes the GL5 EP test), in FWD applications you do not need an limited slip additives.

Cheers,

Guy

 

[scullyg40]

I personally wouldn’t put elf oil in the box as it won’t stand the temps a plate diff will generate.

I found the data sheets for both Elf 75W80 and Redline MT90.

https://total-cdn-lmdb.afineo.io/tds/TDS_ELF_TRANSELF-NFJ-75W-80_NQ7_201410_EN.pdf

https://www.redlineoil.com/Content/files/tech/MT-90_GO_PROD_INFO_2020.pdf

What I can make from this is that the Viscosity Index from the Redline is higher, ie 200 vs 175, which means that the viscosity remains more stable as temperatures change.

Kinematic viscosity at 40 degrees Celsius is 47 St for Elf, and 82 St for Redline.
Kinematic viscosity at 100 degrees Celsius is 8,5 St for Elf, and 15,5 St for Redline.

So all this tells me is that at both temperatures, the Elf oil is thinner. I haven't got a clue which temperatures will be reached with or without a plate diff inside a gearbox though.
@NorthloopCup But is this what you mean with that it won't stand the temps a plate diff will generate? Or will the oil genuinely burn or something after hard use? I was hoping to find a temperature range or something in the data sheets, but all I can see is the pour point, which is not interesting to me.