GL4 vs GL5

[Mr.Fork]

(cough) so when I'm driving hard and like an idiot, this classifies?

Thanks for clarifying that point mb-man.

 

[moribundman]

I wouldn't know about your car. I can touch my car's transmission casing without burning myself, not matter what, so temps get nowhere near 250 F.

 

[wantin150]

FWIW, my Toyota transmission specs a GL4 or GL5 rated MT fluid. I ended up with a real notchy and difficult shift with the GL5 Amsoil SVG. I tried their GL4 rated (MTG?) fluid which was better. I finally swapped it out for Redline MT 90 and haven't looked back. I have it in both my Toyota gearboxes. I am in no way bashing the Amsoil. I just didn't care for it in my application. I run their GL5 SVG in the rear diff of my Tacoma.

 

[Mr.Fork]

MBM - I'll do that - she does get warm. I've already purchased Redline MT-90 GL-4 fluid. I plan to swap it over the next week or so.

 

[o2man98]

The Subaru Impreza 5 mt requires GL-5 fluid. Is there any harm in running GL-4 in this application?

 

[JohnBrowning]

Most gear lubes are dual rated like GL4/GL5 and are not harmful to yellow metal at all. If you want a GL4 you can easily order it from Redline,Amsoil,Specialty Formulation and many more companies. In the past in everything Toyota my family has owned we used regular GL5 dino gear lube and never had an issue. Latter we switched to M1 gear lube wich was then just GL5 rated. Then went to Redline for years with no problem at all. Recently I have tried Royal Purple MaxGear and it too worked ok and was GL4/GL5. The best product to date though that I have found for transmissions is Redlines MT90/MTL blend the ratio vary's depending on how thick the OEM fill was.If a company like Toyota tells you that either GL4 or GL5 will work fine use what ever is available and shift fine.