Sorry if this has already been answered, but I am going to change my oil this coming week sometime and I have read all the threads about not using GL-5 oil in the 2003 350z because it messes up the synchros. Red line makes an oil


Now it is a GL-4 oil, but it says fully synthetic on the front. Is this oil safe to use?

 

Redline MT85 (as linked) has the correct viscosity for our trannys and is safe to use.

 

Thank you!

 

Speaking of Redline Transmission oil, i've ordered some for my HR tranny but been confiscated at the Airport

 

try motul works great on my transmission once its warmed up.

 

I've used motul gear 300 and have used Nissan fluid. When i first got my Z i put nissan fluid in it. It was pretty good once warmed up, but not very good for winter/cold weather driving. Switched to motul, experience slightly better shifting and was a little better in the winter/cold weather. I have recently put in GM Synchromesh and have been amazed by the difference it has made for my car. It doesn't really require a warm-up that i experienced with the other fluids. It's made a HUGE difference in how smooth the gear changes are and is very reasonable price-wise ($39 for 4 quarts from my parts guy at the Chevy dealer). I would HIGHLY recommend GM Sychromesh for most manual transmission applications, it's the best product i've came across for manuals.

 

The MT85 is good stuff. I used it for awhile. The thing you have to remember is just to warm it up and it should be smooth. In the cold, it is a bit stiff to get in gear sometimes.

 

amsoil in the tranny is ****

ive tried redline, and motul.... idk which one i like better

 

They're all good. It's a matter of brand preference.

I had the Redline fluids applied at the 30k mile service.

 

Dude I just put Nissan fluid in my trans 107xxx miles and shifts beautifully.I would just the oem fluid if I were you.

 

I noticed that too. It wasn't as stiff to shift with the OEM fluid.

 

Interesting. How long have you run it now? Did you cut it with some 90wt to bring the viscosity up? Synchromesh by itself is about 80wt and technically too thin for the Z gearbox so if you've had it in for a while I'd be interested in how it looks, possibly a UOA.

I have to do this soon and I'm considering a 50/50 mix of synchromesh and 90wt. I've had amazing results in previous cars with it as well. I wish Specialty Formulations was still around. Their MTL-P was supposedly the nectar of the gearbox gods...

 

I used Synchromesh in my Civic as it was a popular alternative to the OEM fluid. However in my Z I used Redline MT-85 and have not looked back since. I actually switched it out after I had OEM fluid in my tranny for about 1-2k miles so I went from basically new OEM fluid to new Redline and I gotta say it made a world of a difference. I will not use anything else but Redline in the tranny now. I also have Redline in my diff and so far no complaints with that either.

 

I put straight GM Synchromesh in my transmission. Looking at my records I put the fluid in on 7-21-14, so it's been a few weeks. I believe, GM Synchromesh was originally designed for corvette transmissions so I doubt I will experience any problems using it in the Z. It's safe with brass synchronizers as well which is a must with these cars. If your debating on using synchromesh, do it and thank me later. It made such a drastic difference in the shifting of my car and is a joy to drive now, I always hated having to wait for the transmission to warm up. I'm still careful with it until it's up to running temp but it's just because of my old habits of the other trans fluids I tried. Also, I'm not sure if I'd be mixing fluids together.

 

i replaced the manual transmission fluid with Redline MT90 after i just bought my Z at 50k miles because 1st to 2nd was sometimes a bit notchy. it is now MUCH worse so i am changing back to OEM fluid ASAP!!

 

Well, could be the MT90; but whatever the reason, that's the wrong weight. The recommended fluid for Nissan transmissions is MT85 with an effective SAE weight of 75w-85. Will be interesting to see if going back to Nissan GL-4 75w-85 solves your issue.

 

i just spoke to the dealership and they said they only sell the OEM in the 20L drums but to not even bother because its just rebranded GL4 75w-85 castrol oil anyways that can be bought from most auto parts places in 4L bottles. Might just try another brand then and do it myself.

 

Well at least you didn't use GL-5, but why on Earth would you get MT-90 instead of MT-85 with all of the information easily available for you to see that MT-85 works best for the Z?

Hopefully no damage occurred. Nissan put GL-5 in my car and I blew out 3 synchros in under 100 miles.

 

I read that a lot of people had used MT90. But, yup should have gone with the MT85.

The workshop manual says use either 75-85 or 75-90 so MT90 is still within the recommended weight so will be surprised if it damages it. The dealership is replacing it with OEM stuff on monday.

how could you prove that they put GL-5 in it and did they repair everything for you after that?

 

my cars going to nissan on monday for some OEM MTF. I was thinking about putting in some Molyslip additive as well to help smooth the gear changes. Has anyone had any experience with this additive? ive only heard good things so far...