XPR 10w40 for transmission.oil.
 

So Saturday I called the reps at royal purple to see which gear oil is right for my 370z. While I was on the phone I also mentioned about my 6spd tranny oil. He said well 75w90 is what you need, it flows the same at cold weather like the factory stuff. I said I was told tho that it might give me harsh shifting. He said well off the records you can use a hps or XPR 10w40 that has the same additive like the 75w90. I meam I've heard of motor oil for manuals but has anyone tried this or heard of this? If so how do you like it?

Joey

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The harsh shifting that most people have 1st to 2nd or 2nd to 3rd is more because of the syncro then the fluid. I'd stick with the 75w90, since as far as i have read no one has tried otherwise.

Just wondering. All I hear about the tranny fluid is either nissan or redline. At my job I can get royal purple at a good price. I switched out the rear diff and love it

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I assume you have the stock VLSD?
Because that thing is such a POS it doesn't matter what fluid you put in it at all

No unfortunately I have the non lsd

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I would think any synthetic oil of the correct grade from a reputable mfg. would be good.

but the question is using 10w-40 not just royal purple. the beater suzuki i used to own had 75w in the manual but everyone runs atf, i would be tempted to try syncromesh fluid for gm transmissions, they have notoriously bad synchrous unless you run the synchromesh.

I just don't see how such a drastic change could lead to any good. I'd go with something a lot closer to what the engineers specified.

Well all the specs meet + exceed with the royal purple. I've used royal purple before on other vehicles with great results!

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75w90 =/= 10w40. I wouldn't run gear lube in my engine, either - even if all the other specs were the same.

I have to believe that if such a light-weight oil was good in the transmission, the track guys would be all over it (theoretically, it should provide less resistance). So far, I've seen no mention of anybody doing it to the Z. Matter of fact, in my 40+ years of working with cars, I've never heard of anybody running engine oil in a transmission.

But I'm no expert and I haven't heard everything.

If you do decide to go with the light lube, it might be worthwhile to start doing frequent analysis to check for excessive wear.

I agree, you can experiment with something like 85w90 or 75w80. But I would sample the oil after some milage for excessive metal wear or other changes.

I understand. I've heard of some trannys taking motor oil, IE; my turbo Lebaron with the A555 and some honda, Took 5w30. I mean I wouldnt do it to my 370z. I was just curious if anyone has ever done or heard of 10w40 for the 370z. I'm a big fan of royal purple. But some cars like certain oils. Wondering is all

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I ended up switching to 75w90 royal purple, and wow, noticed a big improvement with shifts....so crisp and smooth. Also switched to RP hps 5w30 and motor seems smooth....As odd as that sounds.

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