Redline synthetic 75W-90 (1 Viewer)

[WarDamnEagle]

A question for all you Redline afficionados in Mudland:

Redline lists a 75W-90 and state that this is their standard gear oil which CONTAINS friction modifiers for limited slip applications.

They also list a 75W-90 NS and state that this is their gear oil for non limited-slip applications as it contains no friction modifiers.

Doesn't the labelling seem a little backwards?...but that's not my question.

Question is, can anyone make a case for one over the other for the 80 differentials and transfer cases? I was just going with the 75W-90 NS but as ususal have started to perhaps over think the situation.

My uneducated guess is that one would never notice the difference and that either would work. I am also guessing that many people don't read the fine print and just use the "normal" 75W-90 instead of the 75W-90 NS, thinking that the NS one is for limited-slip applications.

 

[Dave @ Red Line Oil]

In your differentials I would recommend the 75W90, it contains a friction modifier to control chatter from a multi-disk clutch type limited slip when making a slow/tight turn. The friction modifier is also beneficial for both friction and temperature reduction, a benefit in the overall operation of the differentials.

If you are changing the transfer case without the transmission the 75W90 or 75W90NS could be used as well as the MT-90. In the transfer case of a manual transmission vehicle, where a gear oil is called for, I prefer to use a fluid that would be appropriate for the transmission should some exchange across the seal, the 75W90NS or MT-90.

In the transfer case and manual transmission if changing both I would recommend the MT-90. The 75W90NS would be an option and should offer shiftability close to the MT-90 in the transmission.

Sorry for the confusion, the NS refers to Non Slippery, a gear oil without friction modifiers, so not too slippery for the transmission synchros. It will also offer maximum lock-up from a multi-disk clutch type limited slip, beneficial for some racing and off road situations.

Regards, Dave
Red Line Oil

 

[cary]

Regards, Dave
Red Line Oil

Holy cow. If this is the Dave I think it is, he is their chief engineer.

 

[WarDamnEagle]

In your differentials I would recommend the 75W90, it contains a friction modifier to control chatter from a multi-disk clutch type limited slip when making a slow/tight turn. The friction modifier is also beneficial for both friction and temperature reduction, a benefit in the overall operation of the differentials.

If you are changing the transfer case without the transmission the 75W90 or 75W90NS could be used as well as the MT-90. In the transfer case of a manual transmission vehicle, where a gear oil is called for, I prefer to use a fluid that would be appropriate for the transmission should some exchange across the seal, the 75W90NS or MT-90.

In the transfer case and manual transmission if changing both I would recommend the MT-90. The 75W90NS would be an option and should offer shiftability close to the MT-90 in the transmission.

Sorry for the confusion, the NS refers to Non Slippery, a gear oil without friction modifiers, so not too slippery for the transmission synchros. It will also offer maximum lock-up from a multi-disk clutch type limited slip, beneficial for some racing and off road situations.

Regards, Dave
Red Line Oil

Thanks Dave. It sounds like, as I suspected, either will work fine. Based on your response, it appears that you might not be entirely familiar with 80 series Landcruisers. To my knowledge, all US 80's came with automatic transmissions wtih separate transfer cases. Not an expert, but I understand that the the transfer case is geared but does include a viscous coupler. The transfer case calls for 75W-90 gear oil.

In addition, no front or rear differentials were sold in the US with limited-slip. They are either open differentials or Toyota electric locking differentials and the FSM specifies normal 75W-90 for both applications.

I don't think any of the above info would change your recommendation in any way and apologies if I'm attempting to school an expert.

 

[tres0422]

So did we get a consensus?

I am changing my diff and t-Case oil. Don't know how long it has been so I am going to flush it once with a reasonably priced gear oil then drain and put in the redline. Which redline should I use.

stock and no factory e-lockers

Front diff 75W90NS

t-case 75W90NS

Rear diff 75W90NS

sound right?

Thanks,
Tres

 

[IdahoDoug]

If you HAD a transfer case, I'd say you're right. However it is still correct for your center differential - heh.

DougM

 

[Bambusiero]

But the 80 series differentials, axles, and transfer case center diff, are open type, or mechanically locked, there is no clutch plate type limited slip mechanism.
The center diff has a viscous coupler, but that's a whole different animal than limited slip clutch plates, right?