Subaru viscous LSD oil question

[2000wrx]

The rear differential in my 2000 model WRX is of the viscous limited slip type. The factory manual does not specify the use of LSD specific fluids. Are the LSD fluids only needed for the clutch type LSD's as opposed to my viscous unit? The only LSD type syn fluid I can find is a 75?w-140. I would like to use a 75w-90 (recommended) but my preferred fluid is specifically not recommended for LSD's. Once again is this only for clutch type LSD's?

[ August 25, 2005, 03:41 AM: Message edited by: 2000wrx ]

 

[Leo]

Yeah viscous units do not rely on the frictional characteristics of the diff oil itself. So any differential rated GL5 oil would be just fine! You can safely use LSD rated oil in there too. I assume you are thinking of Castrol SAF-XA?

 

[Losiho]

Motul Gear FF-LSD Competition/Sports :

http://www.motul.com.au/product_line_up/gear_box/gear12.html

GL5, 75W-90, 100% synthetic, safe for LSDs. It was recommended to me by the Motul techs instead of Gear 300, as I wanted a 75W-90 that was "GL4 safe" and had less sulphur.

I saw Gear FF-LSD at Autobarn, $26 for 1 litre.

 

[2000wrx]

Yeah Leo I was thinking of SAF-XA, actually its in the diff at the moment but I've always wanted something lighter, also helped along by a recent thread here. I've never seen a synthetic LSD suitable oil in any of the auto parts stores that I frequent, besides SAF-XA. Until today actually when I saw a bottle of exactly the same oil you mention Losiho. Seeing as I dont need the LSD additive I will fork out for a bottle of Syntrax as I know and trust the Castrol ester gear oils, although I'm sure the Motul would do a sterling job aswell.

I visit Autobarn a bit more than I used to because Supercheap Auto aint so supercheap. Sure they really do sell some supercheap junk in there, but the brand name stuff is at least as expensive as anywhere, from what I can tell. Syntrax is about $2/litre cheaper at Autobarn.

 

[bulwnkl]

To give you another alternative if you want to make sure you DON'T get any LSD-oriented friction modifier, you can use RedLine 75W90NS. I do not believe the LSD friction modifier present in a GL5 lube like RedLine's regular 75W90 will cause you the slightest bit of difficulty. Nevertheless if you really want to avoid it their NS is exactly the same as their regular, but without the FM.

 

[SilverGGA]

True. Use NS if you want to absolutely avoid LSD additives.

But I talked to Redline's US rep and he recommended the 75w-90 over the 75w-90NS for viscous diff. He says the NS is fine because the diff is not clutch based, but the regular 75w-90 will reduce operating temp over the NS because the 75w-90 has the LSD additive (more slippery).

quote:

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Originally posted by bulwnkl:
To give you another alternative if you want to make sure you DON'T get any LSD-oriented friction modifier, you can use RedLine 75W90NS. I do not believe the LSD friction modifier present in a GL5 lube like RedLine's regular 75W90 will cause you the slightest bit of difficulty. Nevertheless if you really want to avoid it their NS is exactly the same as their regular, but without the FM.

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[Eddie]

I've been running 94,000 miles in both differentals of my 2000 Forester S that has a LSD in the rear. Absolutly no problems.

 

[Eddie]

Goofed that up. I run Mobil 1 75/90 gear oil in both differenals.

 

[SilverGGA]

I just run Redline 75w-90 GL-5 in my 04 WRX.

 

[unDummy]

There is no need to avoid LSD additives in a "sealed" viscous unit. If anything, I would think that a clutch/cone type friction modifier would act like an AW/EP for reduced wear in a non-LSD or sealed units.