Vasichko

iTrader: (1)

im having a hard time finding gl4. I thought in the 90s they were trying to get rid of gl4?

Jedi54

iTrader: (7)

Redline is GL-4

TeamRX8

iTrader: (25)

correction,

Redline MTL and MT-90 is GL-4

Redline 75W90NS and 75W140NS are GL-5

Redline Shockproof - no GL rating

the other Redline gear oils contain limited slip lube; IMO not recommended

Jedi54

iTrader: (7)

Thanks Team.
Yeah, I recommend MT-90 since it's GL-4

Vasichko

iTrader: (1)

Well, I dont know what the Idumetsu is, Rotary Performance recommended it, but doesnt say what spec it is.

I may just ditch everything and got with some 75w90 Redline all around.

TeamRX8

iTrader: (25)

you have to us the "NS" version in the trans, do not use the standard Redline 75W90 gear oil in the trans

weaves

i just got some royal purple 75W90 for my trans. and on the bottle it says gl4 and gl5 rated, and i know your only suppose to use gl4, is this still ok to use?

O'Renesis

I have been reading up on the transmission oil required for the RX8 and I am a bit confused with the GL4 and GL5 standards. The REDLINE OIL Manual Transmission Gear Oil 75w90NS is a GL5 but has not got the "friction modifiers for limited-slip hypoid differentials" Do you think this is a suitable oil for the 6 speed manual gearbox? On Friday at my trackday I was having gear shift problems. This was after about 20 laps of the course and the RX8 was really really hot. Shifting from 3rd to 4th was very tricky and I had to momentarily stop in neutral before shifting into 4th. Otherwise I got a loud grinding sound from the gearbox. Other gear shifts were OK.
I need to change the gear oil, both the gearbox and the differential. What would you recommend for the diff.?

CosmosMpower

I use RP Maxgear in the tranny and Mobil 1 75W90 GL5 in the diff, no issues. I did try Amsoil in the tranny and it SUCKED, very notchy and stiff so I drained it out in a week.

Rhythmic

Has anyone actually documented problems with Royal Purple maxgear (as in wearing issues)? I am aware that GL-4 is recommended, but according to RP although maxgear is GL-4 and GL-5 it will not cause premature wear in a tranny, including syncros.

I've had maxgear in my tranny for about 10,000 mi. and it is great. Tranny is cooler, quiter, and smoother. I have although thought about a swap for Redline, b/c I used in past vehicles and b/c or the GL-4 only debate.

TeamRX8

iTrader: (25)

https://www.rx8club.com/showpost.php...0&postcount=23

RX8Maine

Despite my post above, the GL4 debate convinced me to swap out the RP for Redline MT-90. Not all transmissins are the same, but I like the Redline better in mine. Once warmed up, all of the shifts are smoother and faster, including the 1-2 (which is still slower than the rest.) When cold, the 1-2 shift was slightle more notchy, but that went away quickly. The RP worked REALLY well in the winter in sub-zero temps. Time will tell on the Redline.