stewartsw1

So I recently had the RJM clutch pedal assembly installed on my g37, then the next day I had the MT oil changed (and the differential). Since then, my shifter has been very difficult to move but gets much better after the car warms up a bit. Anyone have any idea why this might be? I can't see the new pedal assembly affecting this or the trans oil either but I have no idea. I did notice that the car calls for like 3 quarts and 4 ounces and I believe the shop only put 3 quarts in ( i brought my own redline oil with me) but can't imagine that being an issue either. They may have noticed and added some anyways.

JSolo

iTrader: (14)

Where are you and what weight trans oil was put in?

stewartsw1

I'm in northern Virginia and the correct weight was used. I looked it up previously, pretty certain it was 75w-90

JSolo

iTrader: (14)

Too thick for this cold. Either use the stock nissan fluid, or MT85. 75W90 is fine if your typical ambient temp never falls below 45F. I ran MT85 for about a year and a half, ~9K miles, had similar issues in the cold on the 2nd winter. Switched back to stock nissan fluid (in the middle of january), no issues now 2 winters in a row (~5500 miles on the fluid).

stewartsw1

Well that's good to know, thank you. Doesn't the owners manual call for 75w90 though? What is the viscosity on the stock Nissan oil? It's supposed to warm up soon and dont really have the time to get it done again, am I risking any damage by leaving the mt75 until next year when it gets cold again ?

JSolo

iTrader: (14)

From the fsm:


From the owner's manual


75w90 is called for for the diff/rear end. We still got another month and a half of winter here in chicago, so no warm up in the immediate future. I suppose you could shift 1-3, double clutch, or allow the car to warm up more. As I understand it, the syncro's are not doing their job which is why it's difficult to get it into gear (1-2) when the fluid is cold. I suppose this could cause a dangerous situation if you need to get the car going quickly while it won't engage a gear.

stewartsw1

Mine shows something different. It shows 85 or 90. I only chose 90 because it seemed like others recommended it and that's what the shop I brought it to sold me. I can't figure out how to post a screenshot with my phone here but if you go to page 382, you'll see what I mean.
https://owners.infinitiusa.com/content/manualsandguides/G_Coupe/2008/2008-Infiniti-G37-Coupe.pdf

JSolo

iTrader: (14)

^^My pics were from a 2012 fsm and owner's manual. Looks like they updated the recommendation since 2008. In fact, the fsm (for the 2012 MY) has a revision date of 2/2013.

Either way, it's just like with motor oil, if you're in a predominately hot environment, an mfg may recommend using a higher viscosity oil (although it appears nissan recommends 5w30 regardless).

You'll be fine once the weather warms up, but cold temp shifting on a cold trans will be difficult for the time being. I don't know if my experience with mt85 was a fluke. Perhaps because it's a high performance oil it doesn't last as long or the additives wear out quicker. For now, the stock oil has been working good. It's not buttery smooth when warmed up (about 90% of what the mt85 was), but I can shift the car easily until warmed up.