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

 

Redline is GL-4

 

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

 

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

 

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.

 

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

 

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?

 

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.?

 

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.

 

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.

 

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

 

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.