Racing Gear Oil?

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I recently put Idemtisu Racing Gear Oil (pictured) in my Aisin AY6 manual transmission. I beat the hell out of this transmission, and this oil made my shifts much smoother. My question is, would a 'racing' formulation pose any problems for a daily driven car? Like 'racing' brake fluid needs to be changed more often than regular brake fluid because it's more hydroscopic, for example
 

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I would personally be more concerned about whether the synchronized gearbox was intended to use a GL-5 hypoid gear oil. Is GL-5 specified for this vehicle's transmission?

As for the use of a "Racing" fluid - that is likely a marketing claim and not necessarily something that would be less additized based on the expectation of frequent fluid changes. Idemitsu is a highly respected brand and should serve you very well.
 
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Androideka

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I would personally be more concerned about whether the synchronized gearbox was intended to use a GL-5 hypoid gear oil. Is GL-5 specified for this vehicle's transmission?
Good question. The owners manual specifies GL-5, even though it apparently has brass synchros. I have a Camaro, and the old Toyota Tacoma manuals say GL-4 or GL-5. This confused me for awhile but I just trusted the engineers in the end

Good to hear, I figured it was marketing as well but wanted to double check for comfort
 
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Good question. The owners manual specifies GL-5, even though it apparently has brass synchros. I have a Camaro, and the old Toyota Tacoma manuals say GL-4 or GL-5. This confused me for awhile but I just trusted the engineers in the end

Good to hear, I figured it was marketing as well but wanted to double check for comfort
In BMW community people who track vehicles go Redline D4 or MTL.

Also, it is not hydroscopic, but hygroscopic :)
 

Androideka

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In BMW community people who track vehicles go Redline D4 or MTL.

Also, it is not hydroscopic, but hygroscopic :)
I was about to go with the MTL and would honestly prefer it, but was on the fence due to it not being GL-5 like my manual said. Do you know why the cars using this trans would go from speccing GL-4 or 5, to just GL-5? Is GL-4 forwards compatible (is that even a thing?) with GL-5? My knowledge of gear oils is pretty limited, so I didn't want to deviate without feeling confident

Indeed it is, I think I've been saying it wrong my whole life lol
 
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I was about to go with the MTL and would honestly prefer it, but was on the fence due to it not being GL-5 like my manual said. Do you know why the cars using this trans would go from speccing GL-4 or 5, to just GL-5? Is GL-4 forwards compatible (is that even a thing?) with GL-5? My knowledge of gear oils is pretty limited, so I didn't want to deviate without feeling confident

Indeed it is, I think I've been saying it wrong my whole life lol
gl-4 and gl-5 are basically additive levels for protection.
normally only hypoid gears require gl-5 which IIRC has around 250% more of certain additives than gl-4.

If your owners manual says gl-5 then use gl-5
your Idemtisu Racing Gear Oil says its for transmissions so I would assume its properly made to work with synchros etc.

If you are looking for alternatives
Redline 75w90NS
Motul gear 300 (regular not ls)
Amsoil... SVG?
 
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gl-4 and gl-5 are basically additive levels for protection.
normally only hypoid gears require gl-5 which IIRC has around 250% more of certain additives than gl-4.

If your owners manual says gl-5 then use gl-5
your Idemtisu Racing Gear Oil says its for transmissions so I would assume its properly made to work with synchros etc.

If you are looking for alternatives
Redline 75w90NS
Motul gear 300 (regular not ls)
Amsoil... SVG?
^This. Motul is always a safe choice.
 

Androideka

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^This. Motul is always a safe choice.
I'll check it out. I might pick some up for if I get bored and want to drain/fill down the road and use Motul, I've heard a lot of great things about them from people who race

Thanks everyone, it sounds like I'll have no problems with what I have in right now 👍
 
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