laurentj23

iTrader: (1)

Hey all! I have a 05 ZR with 63k miles. Last friday i took it to the shop and changed my differential as well as tranny fluids. I supplied my own fluids with valvoline Api gl 4/5 75w90 for the transmissions. I've noticed that when the car is still cold, it's hard for me to shoft from n to 1st gear or grinding noise from 1st to 2nd gear.

I also heard some whiring noise while driving on 3 rd gear abt soon went away.

Any idea what cause the problem? Shld i replaced the fluids again with a better fluids? Is my tranny going to ****...help.

DavesZ#3

iTrader: (26)

The trans fluid definitely has an effect on the shifting feel. Unfortunately, it's not predictible or the same for everybody. I've tried both Redline and Royal Purple and they are both different than the OEM fluid, neither better or worse overall. Some aspects better, some worse.

There are a couple of big threads on transmission oil change and if you read them, you'll see that everybody gets different results. Everybody has their own favorites and dislikes. About all you can do it try a new one every year and see what works and what doesn't. You may find what sucks today in the cold feels like pure silk next summer when it's hot.

laurentj23

iTrader: (1)

Thanks Dave. Will it gonna cause breakdown on the tranny though due to different fluids? I am just worried abt that.

So what's the different about the redline and royal purple as far as shifting goes? Which one is better?

JCITY

iTrader: (2)

Just a thought...
I'm probably a bit(alot)older than most forum members.I've had more cars than I can remember(even though,I did make a list.It surprised even me).One factor that I can state as is a constant more than not,is the use of OEM stuff on your car.With some car makes,its no difference.But,with MOST,it does.Trans.oils/fluids is one.Best to stay with OEM
unless your driving purpose has changed(racing/track).Some tires are just designed for the car.Same goes for shocks.For some reason,Jaguars just don't feel right unless OEM shocks are used.Some Italian cars need plugs(Lodge)that came on the car or they just won't run right.
So,its better safe than sorry.
Go with OEM.

davidv

iTrader: (2)

Do not expect a vehicle to operate properly until it has reach operating temperature. Thats just common sense.

DavesZ#3

iTrader: (26)

Normally I'd agree with you. But in this case a variance is a good thing. The older models Zs came from the factory with petro based oils. The newer ones have been swapped over to synthetic oils in the trans and diff. Certainly OP can give the Nissan synth oils a try but ultimately he definitely wants to switch to a synthetic, Nissan or reputable name-brand aftermarket.

DavesZ#3

iTrader: (26)

No, as long as you are using API compatible fluids (GL-4, GL-5) for the proper application, no harm will occur. Most people have switched to synthetics because of the lower friction which in these gear based applications reduces drag and gives better gas mileage.

Keep in mind that the VLSD part of your diff has it's own internal fluid which is not affected by your fluid changes.

I'm not sure what is exactly the difference between RP or Redline or if the companies would even publish it. The definitely shift different as I feel it. Like I said, some people swear by different brands that it made their transmission better or worse or no difference at all. Part of it is subjective so who can really say which one is better.

laurentj23

iTrader: (1)

It's common sense but when you can't shift your gear to first or 2nd gear after a fluid flush that kinda makes me worry. It doesn't do that before the fluid change.

I read all the pages about the fluids change. it appears to be a common problems unless nissan oem fluids are being use or motul brand. So if any of you planning to change the differential/tranny fluids, get OEM or Motul from forged performance. Unless you like hard shifting when it's cold.

Thanks for all the help!