- My model of MX-5 is: __ND2 2.0
- I’m based near: __lancashire
- I’m looking for technical help or recommendations on: __
Well i never !
Today i changed the gearbox and diff oil, to be honest i was a bit sceptical what difference it would make on a 15000 mile car.
I expected both oils to be fairly golden and not really need changing. Well…the diff was pretty black and the gearbox was even worse. So changed the fluids for Mazda diff oil and Syntrans Gl4 for the box. The biggest surprise was how much better the shift from 1st to 2nd feels, it was always a bit recalcitrant especially when cold. Mechanical sympathy was always called for, it surprised me really, as the MX5 is renowned for such a sweet gearbox (if the ND doesnt break) .
Well, it just shows what a" box" fluid change can do . Never in all my puff have i changed the gearbox oil on such a low mileage car and felt such a difference.
Very happy man today !
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Glad your gearbox is now working properly. Recommended time for change is something like 30,000 miles or 2 years which ever comes first, I’d guess your car is more than 2 years old. Engine, gearbox and diff oils are hygroscopic, they absorb moisture from the atmosphere no matter if you use them or not which is why manufacturers put the ‘which ever comes first’ clause in the manual.
They both run very hot which is why they need changing a lot more regularly than Mazda suggest. I change mine annually even with such low mileage (<3k) but mine is turbocharged so for what the oil costs me I’d rather be safe than sorry. I also have a gearbox cooling scoop on mine which definitely helps.
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5 years, 60K miles
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Sounds great. I had the same feeling from the off last year when they changed mine (they used the OEM Mazda long life gear oil IS- I saw the drum). I was going to use that Castrol juice (well, Transmax), I even brough it in to the dealership, but I didn’t when I saw they had Mazda’s stuff. Mine was changed at literally the same mileage as yours too.
The diff I had done with the same Mazda SG1 stuff you used for the diff, a year before.
Yeah, it definitely makes a difference. Transmax and Syntrans are the same oil, just rebranded last year. I couldnt get hold of Mazda gearbox oil at the time and the castrol oil had good reviews by other Mx5 owners.
Im going to change both, oil and diff at major service times from now on. My major services tend to be every two years. I dont track it and its not modded,…plus im not as spirited a driver as i once was !
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Jeez that is almost American service intervals, seem to remember 100k miles for a Caddilac in the eighties ! As a heavy abuser of mine, competitions and regular 500 miles drives in a day type drives I tend to do mine early anyway.
Mine is very light use, i bet you do more miles in a month than i do in a year !
Oil n filter once a year and brake fluid aircon service every other year, except ive now added diff and gearbox to the list 
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Hunh! I recently bought oil & filters from the MXParts guys (gr8 service!) and had my trusted garage do the job. As I am considering selling my Mk3 for a new metal roof version, I am considering getting diff & gearbox oil changed. When I asked my garage guy, he said it would be unusual to change oil on these two bits. So now I’m confused: just turned 32k miles; 2 owners - I’m the 3rd and managed to ‘rack up’ 1200 miles per year over the 5 years I’ve had car. Would having a complete service done by Mazda dealer be a good (tho expen$ive) move now? Thanx!
Mines a mk4 ND 2.0, im no expert (lots of people much more knowledgeable on here than me) however it appears that the gearbox in the ND (mk4) are more fragile than the mk3 and run a lot hotter than prevous generations . To be honest, if you are having a service done anyway its not much of a job and not particularly expensive to change the diff and gearbox fluids whilst its on a ramp anyway.
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Ok thanks Jon that fills in a few more ‘blanks’ that I have about buying the RF. I do not need a 6-speed trans - I just want a metal roof! and that retract-ability looks good to me. CHeers
Thats interesting. My NC has done 42k miles and in winter when cold is the same. I lubricaated the gear shift and selector rods a while ago which helped for a time. I was planing on changing it at 50k but will now reconsider.
That is most likely true, but who knows how much ‘internet’ stuff goes with it. It may well run hotter, but does that also depends how someone drives it. Meaning, is it really that much hotter if someone drives their ND like many people do, for a 10 mile spin to ASDA, or a 7.5 miles commute to work?
Get your point, lots of problems can get blown out of proportion to the units sold and no issues presented to the ones where an issues become " a common fault or bad design " because of internet experts. I did a fair bit of research on the ND before buying it …a common theme was a chance of early gearbox failure on the first generstion ND’s , to be fair a lot was USA based but i suppose lots more were sold in the US.
I suppose the initial reason for the post was the real difference in the quality of the shift after a fluid change on a very low mileage car . There are loads of people on here that are far more knowelegable about the ND than me and i will always take away other peoples advice and opinions if i think its valid.
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I’d argue its liable to running hot even under ‘normal’ conditions, in my experience even running at 70mph on the motorway I have felt the heat from the gearbox from within the cabin (this is because for reasons I won’t go into that i had removed the cooling scoop at the time) with the scoop fitted I can’t feel that heat even with the car driven enthusiastically.