mazzotta.al

My 04 Z has about 93K on it. I notice that there is a little bite/resistance shifting into gear at different times. I'm a gentle shifter and am very aware of the feedback I get from the shifter. The bite happens sometimes and not others, and I haven't noticed any pattern on which gears give more or less bite than others. It is all this that leads me to believe that changing the fluid will mitigate this bite. Is this accurate? Would changing the fluid actually affect the bite that I'm getting intermittently? I'm guessing there is some sludge/metal shavings in the fluid that occasionally interfere with an otherwise smooth meshing.

The car is only 2K miles old to me and I don't have any idea if or when the transmission fluid has been changed in the past. I'm planning to have my mechanic do it when he does my oil at 93K.

dkmura

iTrader: (64)

If you have no idea of when the tranny fluid was last changed, then yes, it should be done ASAP. As to whether it helps your shifting, only you can judge after changing the fluid (as most of us have changed it way earlier than at 93K). but an educated guess would be it should improve WITH THE RIGHT FLUID.

As many other Z owners have found, Redline MT85 is a synthetic lubricant with just enough friction engineered in to allow the syncros to operate effectively. I suggest you buy four quarts (just to be sure) in advance and give them to your mechanic, rather than hope he gets "the right stuff".

SQuaLZ

Totally agree. Especially since using GL-5 will destroy your synchros. I am a huge fan of Redline MT-85, as you can see in plenty of posts of me recommending it lol.

I think it's better than Nissan OEM, but if you don't go Redline, I would go OEM.

terrj

iTrader: (2)

Redline MT-85 is some good stuff for the Z , i used it on the Z and never looked back.

HRMoneyPit

Still debating trying Redline or not. I run Motul but can not get into gear till it warms up

dcains

iTrader: (15)

You'll have no problems with the Redline.

HRMoneyPit

But then I worry about how it'll do on track. Cause the car does not skip a beat once it's warm

dcains

iTrader: (15)

I haven't heard of any issues with the MT85 in track use, but maybe the 90W would be better? I used to use the 90W before they made the MT85, and it worked fine here in Florida, so it's surely OK in SoCal. Maybe contact Redline, as they have great tech support.

HRMoneyPit

I forget what weight Z1 sold me but that Motul is way thicker then 90 weight

dkmura

iTrader: (64)

After eight seasons of D2D racing with the Z33, MT85 remains the best choice as a replacement fluid. Talked with my Redline tech sources and they confirmed that MT85 remains the best choice regardless of temps or type of use.

mazzotta.al

Thanks for the replies, guys. I ended up going with OEM 75W-85 that I was able to find online although it seems to be discontinued (is there a replacement OEM because I couldnt find one). Maybe next time I'll try MT85.

Anyway, the car is running really nicely now. Mechanic said the fluid didn't look that dirty, but that doesn't mean the viscosity hadn't broken down over time. Shifting first to second used to be a little notchy and is much smoother now. Shifting into first when rolling slightly also used to be hard and I would often come to a complete stop but is now much smoother. Most importantly, I can shift at higher rpms (5k or so) much more smoothly. Used to feel a lot of vibration in the shifter, and when I would depress the clutch to upshift when I was engaged at 5K or so, the shifter came out of gear with very little force which I didn't like. Anyway, that all seems to be better now with the new fluid. Cheers!

dkmura

iTrader: (64)

[QUOTE=mazzotta.al;10832904] Mechanic said the fluid didn't look that dirty, but that doesn't mean the viscosity hadn't broken down over time. [QUOTE]

Just a FYI since I've seen this same statement in a few tranny lubricant threads and in almost every case, tranny lubricant will never "look dirty". After all, those quarts should be in a sealed, pristine environment and shouldn't be exposed to combustion by-products or other contamination like engine oil. In the past, I've seen racing trannys where severe damage occurred (input shaft fractured, gearsets stripped, etc.) and the tranny oil still looked pretty good on tear down. So keep track of those mileages and change the tranny oil on a regular basis.

mazzotta.al

The "dirty" aspect I would think could be seen would result from wearing the gears if you're jamming the shifter into gear. Little metal particulate would shed from the tranny components over time and make the fluid look dirty. Is this not something that would happen? Rather than a critical failure like you described, small interferences over time might make a more visible contribution

dkmura

iTrader: (64)

Nope- wearing gears and syncros usually results in a fine sheen of material that ends up in the bottom of the tranny. Not to go too far OT, but if you see a golden sheen or other color in the drain pan, it's worth holding it up and swirling it slightly. That lubricant will part and show you anything left at the bottom. Small chunks or metallic filings mean you should strain it carefully and see just how much has come out of the drain.

Unlike engine oil, which has an additive package designed to surround and encapsulate contaminants (hence the color change), tranny lubricants seem different. In my admitted limited experience, even severely used racing trannys (with worn dog rings, gears or syncros) never looks as bad as the average engine oil change after 3K miles.