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I'm confused - I'd like to change my transmission fluid, but I'm not sure which is better - Redline 75W90NS or Redline Shockproof?
I'm leaning towards the Shockproof because it seems like it provides more protection.
Which weight of Shockproof would I use - Lightweight or Superlight?

This statement from Redline's website has only made me more confused:
The Heavy can be rated as a 75W250 Gear Oil, but has the lower internal fluid friction of an SAE 75W90. The LightWeight can be rated as a 75W140 Gear Oil, but has the lower internal fluid friction of an SAE 30 motor oil. The SuperLight can be rated as a 70W90 Gear Oil, but has the lower internal fluid friction of an ATF.
Does the Shockproof gear oil have a GL-5 rating? Would this ever be a concern if a warranty repair was ever needed?

Thanks

:D
 

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Superlight is what Cobb tuning says to use if you're going with the Shockproof. It is not GL-5 rated, which I guess could be an issue with the warranty.

Please see the Powertrain Tech. Ref. thread at the top of the forum for more info. BUT that info won't tell you which to use. People have used both - with and without success. It seems to depend on your particular tranny combined with your particular driving style. I use the Shockproof Superlight and it seems to be working well. But others have used the 75-90NS, MT-90 and Shockproof Lightweight, all with success.

Chris
 

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I believe our tranny calls for 70W90, maybe 75W90. As such the ShockProof is overkill. ShockProof was developed for differentials where there is a tremendous amunt of shock loading placed on the gear teeth. I don't think it was intended to put in trannys with synchros and their particular needs.

I'm not saying it won't work, in fact I bet you even power steering fluid will work for a while, but that is not what we want.
Since the tranny, front diff and transfer case are all part of the same enclosure you need to accomodate the lowest common denominator, that is the tranny. That means 75W90 NS (for non limited slip additive) is the best choice. Limited slip fluid intended for locking diffs in our tranny won't cut it since it will keep the synchros from correctly engaging. Nor do we need limited slip lube for the diff since I believe our front diff is open.
 
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