Gearbox Oil - Redline lightweight or heavyweight?

[ossy]

Hi,

Which gearbox oil would be recommended for me to use, Redline shockproof lightweight or heavyweight? It's for a R33 RB25DE that will be getting turbo conversion soon. Planning on using this gearbox, so want to make it last unless I can find a GTST one for a decent price. Doubt the oil has ever been changed lol.

 

I'm able to shift fine when changing gears slowly but if I change quickly, it'll usually crunches 1st to 2nd and 4th to 5th. Would this be classed as slightly bad or really really bad? It doesn't pop out of gears or anything as other posts and threads say.

 

Also I've noticed alot of these gearbox oil threads threads are a couple of years old now. Has anything changed since and is a better oil available or is Redline still the best to go for?

Thanks.

[Duncan]

redline lightweight is good for improving shifting in boxes which crunch on fast(er) shifts due to worn synchros.

I would steer clear of it in new or rebuilt boxes with good synchros as it is not recommended for synchro boxes by the manufacturer

[ossy]

Well that sounds like mine so I'll try out the lightweight instead of the normal stuff.

 

Is the heavyweight not recommended then?

[TXSquirrel]

Redline's light/heavy weight are "no turning back" options.  Once you start using either one it will begin to eat into the synchros.  Try their MTL first to see if if the crunch improves for you, if not go for the light/heavy weight.

[Dobz]

CORROSION PROTECTION The extreme pressure chemistry used in many gear oils can be corrosive to brass and bronze used in synchronizers and bushings. Most gear oils are corrosive at temperatures of 200°F. Red Line Gear Oils are non-corrosive up to 300°F and the MTL® in excess of 375°F. A corrosive gear oil can shorten synchronizer life by half and can also contribute to rust problems.

https://static.summitracing.com/global/images/instructions/red-synthetic gear oils.pdf

Also Redline only specifically say the Heavy Shockproof isn't recommended for most syncro boxes due to it being too slippery.

Go for the Lightweight, be sensible by not slapping gears and the gearbox will be fine. If you ever put a decent replacement in then go to a standard gear oil.

[GTSBoy]

I have nearly 10 years of Redline lightweight in mine. It's fine - for a gearbox that wouldn't change gears at all with normal gear oil when we first installed it.

[admS15]

2 hours ago, GTSBoy said:

I have nearly 10 years of Redline lightweight in mine. It's fine - for a gearbox that wouldn't change gears at all with normal gear oil when we first installed it.

Redlines new poster boy, they should sponsor you.

[alexj]

I have a thousand or so trackday laps on my r32 running redline heavyweight shockproof. The box shifts the same as when i started.

[ossy]

Thanks guys, I'll give the lightweight ago. If I still have problems, then I may give the heavy one a try but will keep my eye out for a gtst box. It's not going to be trashed or anything so should last a while.

GTSBoy, you sold me on the lightweight with that lmao

[tsuokun]

A bit late for the party.

I got a RB25 box that had done some 160k KMs when I installed it. After the swap I decided to first go with some Castrol 75w-90/140 something-a-rather (recommended type anyway) and it was crunchy as hell. Synchros were definitely on the evening side.

So I put in the MT-90 Redline and while it still tends to give you a bit of a nudge when shifting, it works like a charm now for the most of the time and allows easy mid-powerslide shifts from 2->3.

There is talk of HW and LW fluids here, but are these two different from the MT-90 I'm using?