Differential oil change

  1. My model of MX-5 is: ND 1.5 SEL
  2. I’m based near: _NI
  3. I’m looking for technical help or recommendations on: _Differential oil change

Owners manual states that differential oil change is necessary if the differential has been submerged.

Got caught in torrential rain yesterday and along with other cars ahead of me had to drive through a flood of deep water over several car lengths.

Hard to say how deep, but water level probably less than half way between ground and wheel axles.
Able to drive through the water without incident with the water cascading up from under the wheel arches.

New experience for me and personally I don’t consider the differential to have been submerged and therefore unlikely that water has got into the diff oil through the differential breather valve.

Am I being optimistic?

If you’re UK based, the 1.5 ND don’t have a limited slip diff.

Does it mater if there is no limited slip?

It doesn’t matter at all. I would say it’s worth changing the oil and is easy to do. The differential takes .6 of a litre so you’ll need 1 litre of oil and I recommend Miller’s CRX 75w/90 NT+.

Had booked our Mazda 3 into our garage of choice for new brake pads on Wednesday next.

Will show them the dash cam video of the “swim” through the flood then and broach the need of an oil change. Hopefully I will be ok to drive the mx5 until then !
The service schedule quotes Mazda Long Life Hypoid Gear Oil SG1, but no spec for alternative oil grade. 75W/90 sounds right, is it GL5 spec?

Hi E,
It is generally considered to be best practice to change the diff oil on the ND on a regular basis due to the high stresses that it takes. If you do high mileage then every year would be best, lower mileage then may be 2 or 3 years would be reasonable.
You are correct in that Mazda do not recommend any other oil so if it is still under warranty then it would be prudent to use their oil just to avoid any ‘confusion’.
:heart:

If you’re at all handy it’s pretty easy, just from under the back of the car.

This is the oil

https://www.mx5parts.co.uk/diff-genuine-mazda-long-life-hypoid-mk4-p-4571.html

Just need a 23 and 24mm socket, a container to catch it and a fluid pump to put it back in with.

2 crush washers also

https://www.mx5parts.co.uk/differential-gearbox-drain-plug-washer-models-p-3140.html

I’m past my three score and 10. Even though 70 degrees Farenheight equal’s 21 degrees centigrade and my mind is willing, unfortunately my body is not. Days of working on cars are over!

Anyone who gets their MX5 serviced by Roddesons will be aware that from the factory the diff is under-filled. Rodders showed me the miserable trickle of greasy treacle that came out of my diff which was shocking.
Change the diff oil!

1 Like

Thanks all, Diff oil changed today.
Next problem will be the worn rubber bushes in the rear wheel hub carriers, but that’s another topic for another day.

And I’ve read posts/youtube videos where it came out fine…