With mine it isn’t just notchy. The first half dozen changes from cold are almost impossible. If I try to change 1st to 2nd normally, say 10mph, as you would in any car it just won’t go. And I mean it absolutely will not go into 2nd. The only way is to change at like 1mph with revs idling. It’s quite an effort to pull the lever out of 1st as well. 3rd and above are fine. After a few changes 2nd will go but is a bit stiff and notchy. Fully warmed up there’s no problem.
It’s a month since I changed to millers 75w80 and it is definitely worse. But this may be because the temperature has dropped so its even colder to start with.
They need to be warmed up to operate well, the trouble is ofcourse we often don’t have the time to sit there and wait for the car to warm up. Mine is stiff, but not impossible for the first few minutes/miles but frees up no problem after that (even with the 75w140 i run).
My MX-5 2019 has been serviced yearly by Main Mazda dealer , as it is due for service now and it has done a total of 21335 miles , I called the service department to ask why it has never had the gear hydraulic or diff hydraulic replaced , to my surprise he said it is never in the MX-5 service manual to be replaced with this milage but it is recommended to replace the brake fluid every 2 years. I was left speechless.
My independent guy was surprised I wanted my gear and diff oil replaced. He usually only gets asked to service automatic boxes. In any case, he put some 75w90 spec in both my gearbox and diffs today and it drives fine.
For the avoidance of any doubt, i’ve seen a handful of reports of cars within our facebook group with failed differentials. The common outcome being the oil had never been changed.
After a couple of months trying to just live with the gearbox issue I decided I couldn’t stand it any longer. My 2nd gear was completely unusable for the first couple of miles and I was changing from 1st to 3rd to avoid it which is just silly. So I bought some castrol transmax 75w90 GL4 which was on offer on Amazon and had a local garage redo the old change for which they charged me 20 quid cash! Went for a drive this morning and it’s much improved. The first few shifts are still on the stiff side but I can now use 2nd again without too much trouble. Granny shift works fine and it warmed up in no time so I’m happy with that.
I believe the problem with the Millers was that it was GL4/5 and everything seems to point towards a dedicated GL4 being very important. I’d have gone for redline but it’s out of stock in most places and costs £35 a litre compared to £13 for Castrol. Opie oils recommends Castrol when I put my reg in by the way.
These boxes do appear to be very sensitive. I still think mine was better with the original oil before any change and kind of wish they’d left it alone. But it’s certainly worth doing some research before deciding which oil to use.
I took a punt on buying some cheaper Castrol 75w 90 earlier this year with the view of changing mine next year. Whilst the ND hasn’t got a silky smooth change when cold currently, it’s not bad, could be better when warm too. It’s got 75w 80 Millers in, last owner did the change around 3 years ago, so let’s try the Castrol I thought.
