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I use Lighweight shockproof instead. It definatelly help with the notchiness.

I use MT90 ... the scoobydoo wrecks owners like shockproof.

I asked this very question of the Redline tech staff a couple of weeks back.

They recommended MT-90 as it is a RWD needing GL5 lubricants.

I just checked the Redline website for their mx5 recommendations. The tech sheet has MTL for all the listed models.

Adam, did the tech (or could you) elaborate on reasons for MT-90? Whats a GL5, and why do I want it in my box?

I'm planning on doing the oils this weekend, while I'm putting on the new exhaust

I used their recommendation request service asking this question....

>Transmission Type:Mazda 5 speed manual
>Issues : 3rd gear syncho is not as good as it
>should be. The shift is fine if you take your time, but shifting
>quickly will get some gear snatching.
>Recommendations : I thought MTL would be the way to go, but I note that
>it is not recommended for RWD gearboxes. 75W90 is the choice in RWDs.
>My concern is that the MX5 is closer to the loads on a FWD gearbox than
>a traditional American RWD car.
>
>What do you recommend?

Redline came back with this...

Adam,

Thank you for contacting Red Line Oil, in your Miata transmission I would recommend the MT-90. The MTL is a lower viscosity than called for and is not recommended for use in RWD differentials that require a GL-5 lubricant. Do you know what fluid is currently installed? From your symptoms it may be too slippery for the synchros.

Regards, Dave
Red Line Oil

Thanks for that Adam.

Looks like the consensus is the MT 90. I'll give it a go.

Ok now I'm super confused and my searches on this site for a new oil are sending me nuts

My Mazda MX-5 Miata - Find It. Fix It. Trick It book mentions that MTL is a preferred choice and I recently contacted Redline for what oil to use between MT-90 & MTL and got the following reply:

Hi Brad,
Thanks for your enquiry.

The MTL and the MT90 are both GL4 manual transmission oils - simply of different weights. MTL is recommended for your vehicle based on Mazda calling for an 80 weight GL4 gear oil for the transmission eg a 75W80 or 70W80.

MT90 is a 90 weight gear oil (a heavier version of MTL). Putting in too heavy an oil for the syncros can make shifting gears stiffer although in situations of severe hot climate or towing (which wouldn't apply to your vehicle) some mechanics choose to beef up the 80W specified by Mazda by using the 90W instead. This is mostly not a problem for 5 speeds, but as a rule of thumb - 6 speeds will usually always have a shiftability problem if a heavier oil is used. I recommend you stay with the MTL.

If you are racing or doing club race days you can upgrade from the MTL to the Superlight Shockproof oil (yellow in colour). The Shockproof oil has the similar flow of the MTL but is specifically a racing grade oil where manufacturer specifications don't even come into it, designed for highest gear tooth protection in shock loading conditions such as a racetrack.

Hope this answers your question.

Now maybe its just me but that seems to be exactly the opposite to the Redline response posted above.. I have a 98 NB with the stock 5 speed so is the info in this response valid for my car?

Any help would be great as searches on this topic really really don't help!

I've been running MT90 in our 98 NB for about 8 year without dramas. I think I chose the MT90 over the MTL because of the hot W.A. climate.

I just put shockproof blue in the 6 speed, chalk and cheese compared to the goo that came out of it.

AJ & Boags have been for a spin in it since, Boags walked away with my spare 2 litres (which I may add he hasn't paid for ). This was at the last dodgy day at Jules.

source it from here

or pay a bit more and probably walk in and get it here

Thanks for the advice and links guys. From the discussion I had with Redline the 5 and 6 speeds seem to react differently to the different oil types however as I'm in Brisbane with our hot weather maybe the MT-90 could be a goer..

Anyone else want to through a few cents worth of advice in?

I have just changed to Shockproof in my 6 speed and cannot believe the difference that it has made to the shift quality.
I have been really dissapointed with the 6 sp from that point of view and but it is great now.
Cost me $75 to have it changed.

Peter

tuned_to_fly wrote:Anyone else want to through a few cents worth of advice in?

I've been using Superlight Shockproof (Yellow labelled bottle) in 5 speed GB & Torsen LSD since checking with Redline Australia in early '06.

How many bottles do you all buy?

Redline says I need 3 bottles for the gearbox

because the gear box requires 2L and Redlines bottle is 1 US Quarts = 0.946L

I'm thinking of getting the MT-90

What does everyone use in there diff?

Manual Gearbox MTL (* Light Shockproof) @ 2 Litres = 3 US Quarts

Rear Diff 75W90 @ 1 Litres = 2 US Quarts

http://www.redlineoil.com.au/oil-finder-detail.asp?CategoryID=3582&ProductID=5808

I've used both MTL and MT90 in an NA8 gearbox. Both were great and there was b***** all difference between them.

Im using MT90 from the GB ages ago quite happy with it...