Doing an oil change on my 4th gen rear torsen. I have some 80w 90 conventional and also have 75w 90 synthetic. I know 75w 90 is what it calls for but is there anything wrong with using 80w 90 conventional?

 

Nothing really "wrong" with it; OTOH if you HAVE what it calls for, why NOT use that?

The Torsen doesn't have clutches, so it's insensitive, at least in that way, to the difference between dinosaur juice and the modern stuff. Modern lubricates better though; I always use that nowadays whenever possible. Let the dinosaurs rest in peace.

 

Funny story, Being the cheapskate that I am (broke) I purchased some Super-tech 80w 90 at my local Walmart for 5 bucks a bottle which is what I was going to dump in the torsen but before purchasing I was waiting on a guy to respond back to me that had a bunch of gear oil for sale at 5 bucks a bottle, he didn't respond so I went to the Walmart, few minutes after leaving walmart he messages me so I go ahead and pick up 4 more bottles for 20 bucks. Yeahhhh. I was under the impression that our fellow dinosaurs lubricated better for some reason? Well now I cant decide what to put in it, haha. Is it right to assume 80w 90 would be thicker when cold thus making my car slower when cold compared to the 75w 90 making my car faster when cold, ahhprobably the difference is so tiny that I wont even notice. Just one of those things that itch the mind.

 

The difference in "thickness" between 80W-90 and 75W-90 is minimal to put it mildly.

Ah yes, our fellow dinosaurs... I remember when mammals were little skittish things hardly bigger than mice, hiding in the daytime so as not to get stomped. Then the asteroid came and the other political party won in a landslide. The world was never the same again.

All the same, looking at your pic, I'd put the Mobil1 in. If those bottles are full they should do the trick. If not, top it off with the Red Line and/or the other synth. Synth here is the operative concept.

Save the Super Tech (not that it's bad or any such) for less critical applications. Particularly, those that don't reach as high a max temperature. That seems to be the most compelling factor arguing against dino juice. Hell, they couldn't even handle an asteroid.

 

You got jokes Sofa 75w 90 it is. Will post pictures of the mobil1 bottles with seals and being poured out just for you Sofa.

 

Depending on what posi unit u have, if it orig, do not use synthetic gear oil. I installed a Yukon DuraGrip in my 1984 T/A. Document states NO Synthetic gear oil

 

That's a lot of malarky too.
Certain differential companies and cam companies say "don't use synthetic oil", even though it's superior to conventional oil.
They're stuck in the past and perpetuate wives tales...

 

Read the title of the post.

We already know from this, what we're working on. What might be "appropriate" or even "recommended" for some other differential is IRRELEVANT here.

For the record, I haven't used dinosaur skweeeeezinz in ANY rear axle for many decades, and they've all worked JUST FINE anyway. Adding some extra friction modifier is necessary in some cases. THAT'S the reason for the "no synthetic" deal; the companies get tired of groaning & chattering complaints, and to shut the n00b customers up, they resort to that.

 

What Sofa posts, use the Mobil 1 75W-90 gear lube. You will be glad you did. A Torsen is a different animal then a posi, or trac-lock, or Safe-T-Trac or other such limited slip differential.

As noted above, a synthetic oil is recommended for a Torsen. They work best with it. BTDT, still have it...

RBob.

 

If your posi is a clutch unit, like mine, then conventional oil only. Remember when whale oil was used as lubricant for posi - 1970 Chevelle .

 

OEM 99-02 Torsen carriers have no friction materials, so no need for friction modifiers.

Other Torsen units were made with friction setups alongside the gear bias setup.

75-90 or 80-90 are fine in them. No benefit whatsoever to change in weight in a light duty application.

 

Read the title of the post.

Quote:

Torsen Diff which fluid?

We already know from this, what we're working on. What might be "appropriate" or even "recommended" for some other differential is IRRELEVANT here.


Enough already. Give it a rest. He's not working on an Eaton or other clutch-type unit. He doesn't need to hear about it.

Whale oil is STILL used in posi applications. I remember it well. We used to call the additive "whale [offensive slang word for a body fluid]". That's still one of the "friction modifier" options that are available.

But IRRELEVANT here. He doesn't have that, doesn't need it, drivel about it is merely an annoyance.