What’s the best oil for rear differential? 240z

Graeme - CZ

Club Member
Hi guys,

I’m sure there will be a few different opinions on this. Any recommendations for a rear diff oil / spec?

Thanks, Graeme


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Bazzateer

Club Member
Just bought some for mine, GL5 for the diff, GL4 for the gearbox. I went with the Comma brand bought off of Amazon.
 

Graeme - CZ

Club Member
Just bought some for mine, GL5 for the diff, GL4 for the gearbox. I went with the Comma brand bought off of Amazon.

That’s precisely what I did first time around - Comma too. Now thinking my 48 year old diff could do with some gourmet oil. Got Redline MT90 for the gearbox. Someone mentioned Motul to me for the diff.


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Paul_S

Club Member
I've done a lot of reading about gearbox and diff oils on here the last few weeks.

As said, GL-4 for the gearbox (not GL-4/GL-5, use GL4 only) and use GL-5 for the diff.

The other thing I learned was Redline is best for the US spec 'box with brass (bronze) synchros. If you've a UK 'box with the 'Porsche' synchros then other oils are available.
 

Graeme - CZ

Club Member
I've done a lot of reading about gearbox and diff oils on here the last few weeks.

As said, GL-4 for the gearbox (not GL-4/GL-5, use GL4 only) and use GL-5 for the diff.

The other thing I learned was Redline is best for the US spec 'box with brass (bronze) synchros. If you've a UK 'box with the 'Porsche' synchros then other oils are available.

Yeah, I’ve got a US box - hence the Redline GL4.

What GL5 did you go with?


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Paul_S

Club Member
I currently have Motul in the diff but I want to change the oil again. I've not decided whether I'm going for the same or something different.
 

Graeme - CZ

Club Member
Thinking this one...

5a73be3fc6ede0c6ac79b09cb00c7a70.jpg



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Paul_S

Club Member
That looks good. Not a bad price too. I might follow your lead :)

It's a shame it doesn't come in a squeeze plastic bottle but I kept one of those back from before so I could re-use that. I found it's tricky to top up even with one.

And the usual advice which is worth repeating every time - check you can remove the filler plug before you drain the oil!
 

Graeme - CZ

Club Member
That looks good. Not a bad price too. I might follow your lead :)

It's a shame it doesn't come in a squeeze plastic bottle but I kept one of those back from before so I could re-use that. I found it's tricky to top up even with one.

And the usual advice which is worth repeating every time - check you can remove the filler plug before you drain the oil!

Oh yeah, I made that mistake before. I suspect you can’t on most, and need to remove some bolts holding the diff in place so you can move it.


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Paul_S

Club Member
My car has a non-standard diff rear mounting and I can just about fill the diff with everything in place.

I suppose you either need to make sure you the diff is level so so you know how much to put in, or have it higher at the rear and fill it with the correct amount.
 

toopy

Club Member
I used this in my gearbox yesterday

https://www.amazon.co.uk/dp/B0068O6I4E/ref=cm_sw_r_apa_i_ccd1Eb16ZTBEQ

I'd planned to use this in my diff...

https://www.amazon.co.uk/dp/B0050SRNXO/ref=cm_sw_r_apa_i_ned1EbSPAKE8A

but having read this thread I'm having 2nd thoughts!

I'd say you were bang on the money with those two, as and when i replace mine, for the box i was going to use the popular MT90, but now having read more about it on another thread on here, perhaps not being as good as expected for the synchro operation, i will go with the Syntrans instead.
 

Makesy

Club Member
Wait...is the consensus that I should use it in the diff or shouldn't?

It says it's GL4+, so I'm quite confused as to whether it's up to the task.

3690e0a20840debc2ded73f47f9c2b01.jpg


Thoughts welcome!
 

Graeme - CZ

Club Member
Wait...is the consensus that I should use it in the diff or shouldn't?

It says it's GL4+, so I'm quite confused as to whether it's up to the task.

3690e0a20840debc2ded73f47f9c2b01.jpg


Thoughts welcome!

Depends if you have a USA or EU car. The gearbox’s are different.


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Rob Gaskin

Treasurer
Staff member
Site Administrator
That is transaxle oil so it's a compromise because it has to lubricate a gearbox and diff. It may not be a problem with our mileages but ......
 
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