2010 g37 sedan sport - best mt fluid?

[barnejo]

i have a 2010 manual g37 sedan with 93k on it. stupidly, while at the dealer, they recommended replacing the mt fluid and i agreed. from that day onwards (5 mo's), whenever the car is cold, it is very hard to row through the gears, with some gears (2nd, 5th and reverse occasionally) even grinding. the transmission also whistles while driving cold. once it's warmed up, it shifts fine and the whistling disappears.
the dealer swears they used what nissan recommends (75w85) but with winter coming, i'm concerned i won't be able to drive until the car is fully warmed up. does anyone have suggestions for a good mt oil that could possibly help when the car is cold? like something thicker/heavier? or is this an irreversible mistake on my part?
thx!

 

[TheOilWizard]

My first thought would be, did they significantly underfill or overfill the transmission? Are you able to check that yourself, or perhaps bring it back to them with your concern and ask them to verify. A good shop shouldn't mind if you ask politely.

 

[tcp71]

Tried a bunch of different options (Redline MTL, Ford XT-M5-QS, valvoline, etc) on the CX-5 before settling on amsoil MTF. It was -20C a couple of days ago and no issues with shifting. Felt only slightly stiffer than fully warm.

https://www.amsoil.ca/p/amsoil-5w-3...bMowXUMbDLIzFv0JPDDNDdlpyEtUMSAxoCChkQAvD_BwE

 

[edyvw]

BMW in E90 recommends ATF basically (they have MTF designation) with KV100 around 6. But Redline D4 (bit thicker) proved to be so far darling among enthusiasts and I use it too. Really good stuff.
I would say Amsoil, Redline, HPL, Motul (another darling in BMW community) would all do much better. @Pablo might have some good recommendations.

 

[14Accent]

Not sure about your G37, but I used HPL Cold Climate in my Buick's F40 transmission and it really cleaned up the shift action. The F40 is notorious for being finicky about it's fluid, and while it's not perfect when it's bone cold the HPL helped immensely.

 

[barnejo]

thx @14Accent @edyvw @tcp71 @TheOilWizard for your thoughts. any particular opinions on using motul 300 75w90? nissan recommends 75w85, but i should be fine with a 90, right? amazon has a deal right now on a bundle of 3 (which i think is all i need): https://www.amazon.com/dp/B07NDYYHT8?psc=1&ref_=cm_sw_r_cp_ud_ct_K2CPTDRV6RG92T7WCQV3.

 

[TheOilWizard]

thx @14Accent @edyvw @tcp71 @TheOilWizard for your thoughts. any particular opinions on using motul 300 75w90? nissan recommends 75w85, but i should be fine with a 90, right? amazon has a deal right now on a bundle of 3 (which i think is all i need): https://www.amazon.com/dp/B07NDYYHT8?psc=1&ref_=cm_sw_r_cp_ud_ct_K2CPTDRV6RG92T7WCQV3.

I would use the exact viscosity Nissan recommends. I'm a bit of a purist when it comes to transmission fills and don't recommend deviating from the manufacture.

 

[SubieNate]

Does that trans call for a GL4 fluid? I wonder if the dealer used a 75W85 gl4/gl5 which will be significantly slipperier than a strictly GL4 or MTF rated fluid.

 

[thescreensavers]

Nissan/Infiniti Dealer? They likely would have used Nissan MTF which is 75W-85

 

[CBR.worm]

I've had better luck with Redline MT-85 than with the Nissan fluid. It is still stiff to shift on winter mornings and it will still grind going into 5th or 6th if you push it too hard when cold. I think that is the nature of the beast. I bought this car new, and previously had another G35 6MT that behaved the same way that I also purchased new. I've heard good things about AMSOIL MTF, but I have only run the OEM fluid and the Redline MT-85. These transmissions are pretty robust, but not very smooth or silky.

Make sure it isn't overfilled with whatever fluid you use.