Anyone here running synthetic tranny fluid? or rear end fluid? I'm thinking about making the switch and asked my dealer about warranty issues. They said that they didn't know and to contact NNA about it. Well NNA said that it wouldn't void the warranty unless if it was proven to be the cause of a warranty issue. I'm still kind of worried about all this and didn't know if it would be worth it. Any opinions?

 

im putting redline synthetics this weekend, in the tranny and the rear diff.

i am using a 50:50 mix of mtl and mtl 90-as refered to by another member and the 75-90 rear oil.

i dont think it will void the warantee and many other members have already changed theirs.

 

i want to change to redline transmission fluid. the guy at some motorsports place told me that i shouldnt change till 20k miles or somethin but i wasnt too sure about it. anyone know whats up? i think it would help with the 3rd gear grind that i have now and then...

 

I changed to Castrol synthetic tranny and diff oil and it definately improved the the smoothness of the gear changes. Particularly the change from 1st to 2nd which was a bit notchy when cold. Now much smoother.

I was also surprised at the amount of dirt and metal "chunks" in the oil. I'm g;ad to have got rid of it. Oils were changed at 3.5k miles.

 

I assume switching to a synthetic should give a slight boost in acceleration, as well, because it will be a little "thinner"?

 

Redline cured some notchiness on my 91 300ZX, but I am not too impressed with it in my 350. I still have the terrible notchiness from 1st to 2nd that actually gets worse as the car warms up. In fact, when the car is really cold after sitting over night, my first 2-3 shifts from 1st-2nd are perfect. Once I get a little further it's notchy the rest of the time.

Maybe it's my tranny and no fluid will fix it, but I don't want to keep trying the different oils at a pretty penny and $40.00 dollars a pop to change it.

I have heard good things about Royal Purple and Castrol though.

Please let us know how any change to the tranny fluid helps or hurts your transmission.

 

I also installed Redline MT-90 at 4K miles with the hope of reducing the intensity and/or frequency of hard 1-2 shifts. (very notchy, especially when cold). The Redline didn't do a whole lot; perhaps a little improvement overall, but nothing dramatic. Apexi350z recently posted that he had switched from Redline to Royal Purple 75w90 gear oil, and that it had made a noticable difference in the smoothness of shifts. I'm planning to try the same thing; just picked up the RP at a local shop. I'll have it istalled at my next oil change appointment.
Mika

 

Tried Redline Lightweight ShockProof, tried MTL/MT-90, none helped.. but when I switched to Royal Purple 75W90, it helped a lot!! Gear shifting seems easier, and smoother... I had grinding problme from 1st to 2nd after Redline, but now I have not had the grind yet.. I never had problem from 2nd to 3rd, to 4th, etc..

 

At 12,000 miles
Changed the transmission and differential to Redline. Redline tech said that a 50:50 mixture of MTL and MT-90 duplicates the Nissan specs. Differential 75W/90. I never had any problem with the transmission and there has been only subtle improvement in shifting smoothness.
Changed oil to Mobil1 10W/30-waited for engine to 'break in' with standard oil.
Changed brake fluid to ATE blue--higher boiling point.

 

An interesting note about Royal Purple 75W90 gear oil --
Apparently, it meets API GL-5 service category, which means that it has more extreme-pressure anti-wear additives than GL-4 (recommended by Nissan for use in the transmission). Traditionally, the extra additives in GL-5 make it corrosive to yellow metal (brass/bronze) syncros, thereby doing more harm than good to the transmission. (Note that the differential uses GL-5 - no syncros to corrode) However, royal purple *claims* that this oil is non-corrosive. Provided their claims are correct, the royal purple may provide greater protection for heavily loaded metal-metal contact surfaces, like gear and syncro teeth, than a GL-4 oil.
But who knows... royal purple could turn out to be re-branded Kool-aid. Every manufacturer claims to be 'the best;' they can't all be right, can they?
Mika

 

I changed to Redline Lightweight Shockproof in the tranny and Redline 75W90 in the diff at 2600 miles. I measured a minor improvement in fuel mileage when I made the change. The change in the shift feel was weird; I could feel that the oil was thinner, it didn't completely get rid of any notchiness in the gates, but I have never had any grind or feeling that things aren't right (unless I just missed a shift! ).

I have played around with this tranny a lot (now have 9000 miles) and I have found that, although it may feel a little notchy when I shift slow, I can speed-shift it without complaint. Just another example that this car is easier to drive hard than it is to drive gently. I think the notchiness may be deliberate, to give the tranny a feeling of being substantial, and some people over-react. Personal opinion from someone who has had no real problems.

I decided on the Redline before I heard about Royal Purple. I'm running RP motor oil and I'm considering changing over to it for the tranny and diff too.

FWIW

 

I changed everything at 950 miles to Redline.

Oh search before you post YEAH!!! Here is my thread. Old old.

 

There is a similar thread in the Australian regional section and a post from Nathan, who actually races Z, recommends staying with mineral oil in the gearbox. Nathan has re-built the gearbox a number of times already, and noticed considerable wear to the syncros when running synthetic oil, as opposed to no wear when running mineral oil. It has been concluded that the synthetic oil is too "slippery" for the syncros to work properly.

 

Hi Malcolm -
Thanks for the info... I will have to check out the thread...
I wouldn't be surprised to find that the factory fluid is ultimately the best. Despite what I initially thought, Nissan may have chosen the gear oil very carefully.... why else would they specify such an unusual weight (75w85) as opposed to the 75w90 that is used in most other applications? Seems to me there is a reason that we may just now be coming to understand.
Mika

 

Yeah its called profit.

 

Just changed to AMSOil Series 2000 75W-90 in both the MT and diff. The smoothness and ease of shifting is immediately noticeable. Another plus is one fluid handling both applications. We'll see if the MPG increases boasted by AMSOil are true.

 

has anyone tried the amsoil ATF in the manual tranny yet?

 

don't use ATF in a tranny that doesn't call for it...
Mika

 

good advice malcom.

 

yes, it will be good for at least .02whp, you should be able to feel it on the butt dyno.