08 gearbox lube

[littlefield]

New to me 08 G37S manual gearbox. First thing took it to Lube Stop to get all new slickum. They used Pennzoil synthetic GL4 75W90 in the gearbox. Should be okay per the owners manual. Everything good that afternoon and the next morning (about 65F). That afternoon (maybe 75F) I detect a little reluctance in 3rd and an unmistakable synchronizer gnash going into 5th. Slow, deliberate shifting required to avoid grinding. Same thing the next day; okay in the morning, not okay in slightly warmer afternoon. Parked the car. So, I guess I could take it back to lube stop to make sure there's enough oil in the box. I know these folks can be yahoos but these guys seemed genuinely interested in the car. It's not rocket science and I believe they drained and refilled correctly. Question - are these gearboxes notoriously sensitive to lubricant? I'm tempted to try some RedLine. Are the synchronizers known to be weak? If a different lube either something special like RedLine or genuine Nissan (can't believe that would make any difference) doesnt' work it's back to Texas Direct for some warranty. BTW this is the first time I've ever driven a true performance GT type automobile. Amazing. I'll get the gearbox straightened out one way or another.

[Gilley]

It's unusual but it's possible that the lube might make a difference in shifting, especially since you had no trouble until changing the lube.

You could try a different brand that is GL4 rated and see if that works.

[mogasman]

Hello - I am new to this forum. I have a 2008 G37 S with 6 speed manual. The 2008 owners manual calls for a GL4-rated 80W90 gear lube. GL4 is now obsolete and GL5 is the standard. GL 5 is retroactively compatible. I use synthetic 75W90 with LS package in both the differential and the gear box with no problems.

I am a retired XOM Lube Engineer in the Seattle area.

[Gilley]

I wish Nissan would update the specs on the transmission lube to indicate whether GL5 is ok to use.

[littlefield]

Update - I took the car back to Texas Direct where I got it. Very knowledgeable, professional staff BTW. They called me in the p.m. and told me they had duplicated my symptoms. Good in the cooler morning (even after driving 50 miles), grinds in the afternoon. They also told me the car was still covered under Infinity warranty. Really, a 2008? So I'm waiting until the weather warms up a little and the symptom kicks in and Ill take it to the local Nissan place.

[Gilley]

The powertrain has a 6year /70k mile warranty. However, the Infiniti dealer will have to replace the transmission under warranty, unless there is some third party warranty that is covering it.