Opinions on Shockproof in your NB trans/diff

[michaelz]

Hi everyone,

I bought a '99 NB 5sp a few months ago and thinking about changing the trans / diff oil. I've got a gallon of Redline MTL Shockproof in the shed which is basically a backup bottle. There's just over 3 litres left in there, should be enough for both the gearbox and diff.

Questions is... would be would it be suitable?

I read somewhere MT90 should be used in the diff and maybe shockproof in the gearbox but saw one person on miata.net claiming shockproof is no good for the box.

Any experiences would be great.

TIA,
Mike

[93_Clubman]

Used Shockproof in an MX5 5 speed GB for over 6 or 7 years without a problem, although most Redline users do tend to use MTL or MT90 in GB.

[sticky nicky]

Ive been advised to use Redline shockproof lightweight gear oil in my NA6, was planning on doing it on the weekend.

[Okibi]

I use MT90 in my MX-5 gearboxes but i've heard mixed responses from the "smurfs blood" shockproof oils.

[deviant]

I had a smurfs blood, very expensive 'race spec' oil filled box once, it was awful. Stiff when it was cold and notchy hot.

I use Nulon high performance stuff from supercheap and get fantastic shift quality. The torsen just uses regular GL5 diff oil. My car mostly sees track work these days.

Honestly MX5's are not touchy thoroughbreds and don't particularly need speccy stuff in them.

[93_Clubman]

It was Superlight Shockproof (yellow labelled bottle & yellow coloured oil) that I used back in Jan '06 in GB & diff (Torsen 1 LSD). Redline Aust confirmed via email that it was suitable for MX5 5 speed GB & diff (Torsen 1 LSD). But separately, there has been some contradictory (to Redline Aust) advice from Redline US on which out of MTL or MT90 is best - it's all on here in various threads.

As Deviant mentions, Nulon Full Synthetic GB oil (75w-90 100% synthetic smooth shift plus Nulon G70 GB Treatment) has worked wonders on Slowpoke's MX5 5 speed GB. But generally these & other expensive oils aren't required as the MX5 isn't that fussy. However, there is the odd 5 & 6 speed MX5 GB out there that thier owners aren't completely happy with & they've found that experimenting with oils has helped. Another good example is Silvia, & his NB8C 6 speed, which he feels is transformed since using MT90.

[michaelz]

Thanks for all the feedback

Since I've got the shockproof just sitting there, will experiment with it and report findings.

[93_Clubman]

I've got a gallon of Redline MTL Shockproof in the shed which is basically a backup bottle. There's just over 3 litres left in there, should be enough for both the gearbox and diff.

Used just on 3 quart bottles here, including GB turret.

[sticky nicky]

Ive been advised to use Redline shockproof lightweight gear oil in my NA6, was planning on doing it on the weekend.

Well I did the oil change and I have found that my 2nd gear which was a bit notchy, especially when cold, is definately feeling smoother, so Ill be sticking with the redline

[NitroDann]

My na6 is an NB8B from the flywheel back and uses regular synthetic nulon 75w90, and its fine.

Lots of hoo ha goes on regarding trying out a different combo of gear oil every 6 months in an mx5.

Dann

[michaelz]

oops, forgot to update this.

Turns out I didn't have 3Ls of shockproof for both trans and diff but did manage to find a little bit of MT90 as well.

Most of the lightweight shockproof went into the diff. Had maybe 1.5L or so of MT90 for the trans. To make up the extra half litre, I mixed in the remaining shockproof which I've read on the American forums was a "good mix". At first I thought it was kinda wrong but found enough positive feedback on the mixing to give it a shot.

The oil that was in there was awful and very notchy. Feels much better now though.