When I left for work this morning, the it was 2 degrees outside according to the g35. Even with heating the car up before I left, changing gears is a bitch, and avoiding that damn 1st-2nd click/grind is tougher than usual.

I read somewhere that switching to synthetic manual transmission fluid can make the shifts easier, especially in cold weather. But I've also heard that using synthetic makes the synchros not do their job, which is bad for the transimission. Anyone out there switch to synthetic, or care to elaborate?

Drew
2003 G35 Sedan 6MT / Black / Graphite / Aero

 

Yes, reading over from my350z.com I believe there isn't a real problem switching over to snythetic manual tranny fluid as long as you put the right mix in. I don't think there will be a problem with the synchros. If you go redline you will want to use 2 qts of MTL and 2 quarts of MT-90 in the tranny. You will also want to use 2 quarts of 75w90 gear oil in the rear diff. I plan on making the switch when I do my 3,750 oil change. Those cold morning 1-2 shifts are a real pain sometimes.

04' G35S 6MT Ivory Pearl, Willow, Premium

 

I inquired at the dealership about going 100% synthetic in
the differential. The Technician informed me that the differential
oil that Infiniti uses is 50% synthetic and they did not recommend
going 100% in the differential. Enough said for me.

2003 Twilight Blue 5AT Sedan, sunroof,
Graphite Leather, splashguards,
12 wire Hyper-grounding kit,
350Z intake duct, Stillen Hi-Flow Airbox
Underbody rear diffusers, Drilled aluminum pedals

 

The GM "Syncromesh" is pretty good too.


Andrew, We Miss and Love You! Peace!

 

Just curious andyranck....after you begin your drive in the cold morning, how long before the stubborn 1-2 shifting begins to ease up?

I switched to Royal Purple and on cold mornings I still get a very stiff 1-2 shift, but only for about a quarter mile then it is very smooth without any problems.


Laser Red 6MT Coupe / Delivered by Grubbs Infiniti

 

Okay, I think the problem all along is that I have a quick 10 minute drive to work, and my tranny fluid just never heats up in time (when I wake up and it's 0 degrees). This weekend I was driving around for a few hours, and the 1st-2nd problem was hardly noticeable. Then again, I've noticed that the shifts for me are smoother at 3000 and up, which is how I shift when everythings warmed up. When the car is cold, I don't like the rev the engine at all, so I end up shifting at 2500 and hence the notch and grind for me.

Drew
2003 G35 Sedan 6MT / Black / Graphite / Aero

 

Yeah, that's what I noticed as well. When it's cold in the morning and the tranny fluid hasn't really warmed up yet you need to shift at 3K or higher to avoid that clunking/grinding, especially the 1 to 2 shift. Once you've gone for a bit and the car is warm you can shift lower if desired. Personally I like to shift at 3K all the time when taking it easy. Hopefully the switch to Red Line tranny fluid will help out.

04' G35S 6MT Ivory Pearl, Willow, Premium

 

While I don't have a MT, I recommend synthetic trans fluid to resolve the problem you describe.

In the 80's I had (and raced) an RX7. The trans was very difficult to shift in cold temps. I switched over to Amsoil synthetic and that cold shift problem was cured 100%. Of course the tech will say NOT use it. It is VERY likely he doesn't really know the answer. As long as you use the correct weight oil, you should be fine.

BillR