Red Line 75W90NS GL-5 Gear Oil in the Trans
 

Got my throw out bearing and clutch replaced yesterday by a local Subaru specialty shop and they replaced the Motul Gear 300 (worked great) with Red Line 75W90NS GL-5 Gear Oil in the transmission. The car can barely shift into first now even when warm. Feels OK in the higher gears. Anyone else use this stuff?

Seems they don't know the twins very well if they're using GL5 transaxle lube in a transmission requiring GL3/4.

I have Redline MT90 75w-90 GL4 right now, about 8k miles and I can't point to a difference between it and Motul Gear 300 or the OE fill (both for 30k miles). I'd bet even with the GL5 (which iirc is acceptable per the users manual, please check it yourself though) there shouldn't be an issue if it has enough fluid in the trans.

There may be an issue with the clutch install causing the bad shifting, even great shops make mistakes, talk to them, have them drive it, discuss a fluid change and if that doesn't work have them check their work and inspect the clutch install, there should be minimal or no cost to you, specialty shops live and die by their reputation. Best of luck to you.

GL5 is NOT acceptable by virtue of the criteria which make GL3 and 4 different from GL5. GL5 contains corrosive additives which make it incompatible with soft yellow metals like copper, brass, etc. These additives are what allow it to achieve the GL5 pressure rating for hypoid gears (which a conventional transmission like ours do not contain). Some manufacturers put additional buffers in to prevent corrosion of these metals, which works by coating the yellow metals. However in the case of syncros, their very action removes this coating in a flaking manner any time they are engaged, and thus not only re-exposes them to the corrosive components, but also you end up losing a small amount of the substrate material as the coating flakes off. You will shorten the life of these soft metals by using GL5. By how much, is difficult to know.

There are several quality GL4 transmission oils to choose from, not including Toyota's own 75W LV oil. Why someone would insist on using the wrong stuff is beyond me, but hey - it's a free country.

Thank you for making me look it up.

The users manual states to only use GL-3 for the manual transmission.
p.348
https://www.toyota.com/owners/resour...als/fr-s/2013#

The differential specs GL-5 and Motul Gear 300 satisfies GL-4/5, technically it's not supposed to be in the transmission according to the manual and I can't recall what made the majority of the community agree it was ok...

:bonk:

I have been reading threads on that recently and thought it was something about metal deactivators in the Motul making in GL-4/5 compatible. Don't know I believe it myself as I haven't decided what to put in my transmission. Debating Amsoil or Redline or just Subaru OE stuff. That being said, majority of the website seems to think Motul would be good in the transmission, I don't know. Just not sure about the detrimental effects in the long run to the transmission synchros...

http://www.ft86club.com/forums/showthread.php?t=21628

http://www.ft86club.com/forums/showthread.php?t=19218

I assume the problem is that people assume transmission lube is the same as hypoid gear lube because they both have gears in them, but it isn't. Specifically, the GL 4 and 5 rating is applicable for hypoid gear use only, which is what's used in differentials and transaxles...it's a meaningless rating for our transmissions, other than indicating whether it would be corrosive to soft metals. Adding confusion to the whole issue is that the rating scale for transmission oil weights and engine oil weights are not the same, even though they are expressed in a similar format (such as 10W-40 or 75W-90). In reality, a 10W-30 engine oil is roughly equivalent to a 75W-90 transmission oil in weight.

You know how reading hieroglyphics is basically impossible for modern humans... yeah well this threads is like that for me.
#ItsJustAJoke

I've had a helluva time at work lately, I'm not a programmer but I saw this last night and it resonated deeply with me.

https://i.imgur.com/KKKnlcm.jpg


I think it applies at some level whenever you become deep into some niche topic.

LOL - I'll be the first to admit that there's plenty wrong with me... :bonk:

Continuing this discussion, Motul's product sheet says "Suitable for any type of seal and yellow material used in gearboxes design. "

https://i.imgur.com/Du5Bg5r.png
https://s3-eu-west-1.amazonaws.com/m...pdf?1492016023

I just looked up the different years of BRZ owners manual for info on this. For 2017 they updated the list to include GL-4 and GL-5. Were there any differences in the manual transmission for the newer model to necessitate the GL-4 or GL-5 inclusion?

2013-2016:
Use either of the following:
• “MG Gear Oil special II”
• Other gear oil that meets API GL-3 or
upper grade and SAE 75W-90 specifications

2017-2018:
Use either of the following:
• “MG Gear Oil special II”
• Other gear oil that meets API GL-3, GL4,
or GL-5 and SAE 75W-90 specifications

*Edit: The Toyota manual for the 2018 86 still says "recommended oil grade is API GL-3. However, API GL-4 can also be used"

Buy Catrol Syntrans Multivehicle GL-4 that is a very good synthetic transmission oil and mates perfectly gearboxes w/yellow metal parts!

GL5 is used in the differential. GL3/4 is fine in the transmission.