NC transmission oil replacement

[franjae]

Hi all,

I decided to replace the transmission oil today. On removal of the filling bolt, quite a bit of oil flowed out. I was wondering if it was previously over-filled and whether if that had anything to do with the 1st gear being difficult to engage at times and the famous 1st to 2nd crunch.

Anyway I have replaced with two bottles of Redline MTL which means it is a little under total capacity of 2.2 litres. I have dríven over 80 kms today and there's no sign of difficult engagement of 1st and the dreaded 1st to 2nd is much tamed. I'm not holding my breath as the oil change made no difference to my previous NB.

Does anyone know if over or under filling makes any difference? I'm not talking big amounts that would cause transmission failure, of course.

BTW, the magnetic drain plug had this big glob of grey mess stuck to it. I've done 13500kms so far.

[Mr Morlock]

I am inclined to think that with a new car under warranty things that are not right should go through Mazda- first gear hard to engage? If someone on this forum tells you a little over or underfill makes no difference it carries no guarantee or weight if something did go wrong. If you told the dealer the box was overfilled you might have trouble in convincing them.

[Richee]

I decided to replace the transmission oil today. On removal of the filling bolt, quite a bit of oil flowed out. I was wondering if it was previously over-filled and whether if that had anything to do with the 1st gear being difficult to engage at times and the famous 1st to 2nd crunch.

Silly question ... but was your car on level ground?

I cannot see how you can fill past the fill hole, unless it wasnt level when it was filled or I am just a total goose .
________
|
|-----O
|________

Fill hole ( O ) half way up side of box
Fill with oil
once oil reaches the fill hole it will pour out the fill hole

Edit : please excuse my poor attempt at drawing

[@ndrew]

I actually reported to the dealer that its bloody hard to engage 1st to 2nd when the car is cold etc. They came back saying they spoke to mazda and they've never heard of such a problem

I've dríven 3 nc's so far and they all have the same problem when the car is cold!!! It’s absolutely ridiculous!!

[franjae]

The only thing I can think of is the fill plug got put back before the over-filled oil had a chance to escape.

Anyway, I have accepted that is how MX5 gearboxes are, at least in the 6 speed ones. I was just wondering if a little over or under does make any difference.

As to whether the car was level, well level enough according to the eye. Did not use a spirit level to measure

[Gramps]

I actually reported to the dealer that its bloody hard to engage 1st to 2nd when the car is cold etc. They came back saying they spoke to mazda and they've never heard of such a problem

I've dríven 3 nc's so far and they all have the same problem when the car is cold!!! It’s absolutely ridiculous!!

Same here, once the oil warms up the shift is slick. A different oil may alleviate the problem - but which one?

[@ndrew]

I actually reported to the dealer that its bloody hard to engage 1st to 2nd when the car is cold etc. They came back saying they spoke to mazda and they've never heard of such a problem

I've dríven 3 nc's so far and they all have the same problem when the car is cold!!! It’s absolutely ridiculous!!

Same here, once the oil warms up the shift is slick. A different oil may alleviate the problem - but which one?

Apparently Mazda have acknowledged this in the states and have replaced the gb oil for customers whom have reported the issue. Shame that Mazda Australia have failed to acknowledge the problem....

[Charlie Brown]

My NC now has 60,000 kilometres up on the clock. It still has the slow syncro syndrome from 1st to 2nd. It's had it since new. It's normal with this box however some cars are worse than others.

I changed to synthetic oil at about 7,000 klms and that helped the stiffeness but the other synchros then became a little slow also. Slipery oil = slow synchros.

For piece of mind Franjae, my magnetic plug also had the build up of grey sludge and the oil was a silver colour.

To my knowledge the only boxes Mazda has repaired are from the '05 model with a bent 3rd gear fork. Luckily mine isn't one of them.

As for under filling by 0.2 litres, I'd top it up just for piece of mind. If you don't want the expense of getting more Redline, substitute with another synthetic oil. 0.2 litres won't make much difference to the Redline oil formula.

[franjae]

Ah yes, CB,

It pays to check the capacity before you rush out to buy the oil. In the NB, the two litres were sufficient. Next time I'll be buying the 3 litre tub....

Overall I have to say the transmission now behaves better, slightly. It is still a Mazda trait unfortunately.