My model of MX-5 is: 2008 2.0 5MT NC, 102,000 miles
I’m based near: Berkshire
I’m looking for technical help or recommendations on: gearbox and diff oil change
Hello all, I’m looking at changing the gearbox and diff oil on my 5 speed 2.0 NC. I’ve found many things online but wanted to ask a few questions before going ahead.
I know you’re meant to use 75W/90 GL4 for the gearbox. Is there any good oil people have used? (I found suggestions of Redline MT90 and Castrol Syntrans Multivehicle but the Castrol seems to have gone and the Redline is only available in a couple of smaller places so was wondering if there was anything else people have used that’s worked well.)
I was planning to do the turret oil too. I’ve read that you need 200ml of oil for it, is there any specific oil I’m meant to use?
Does anybody know of any decent video/text guides for it? I’ve found one that’s alright but if anybody has used one they found was very good then please do share.
Can I get away without a torque wrench and ramps? (I should be able to borrow ramps if it’s easier than a jack+axle stands, but I can’t get a torque wrench).
This for the diff, to spec GL4-GL5 to look out for.
Washers
Not necessary to use a torque wrench although most guides will advise to. You’ll need a 24mm & 23mm sockets for the diff plugs, can’t remember the gearbox sizes I used. Washers required on the drain and fill diff but only on the drain plug on the 5 speed box, the fill is a self sealing plug although you can wrap a little PTFE tape around the thread if you want.
I tend to use a jack (trolley) and axle stands and get the left side of the car off the ground to gain access to the gearbox. It’s s bit of a faff getting the car back down level to check the level once you’ve put fresh oil in the gearbox though. Not very good to use ramps, your front end will be up in the air and obviously not level.
Best of all is try borrowing a proper garage ramp or get it done for you, much easier.
Diff a little easier if your car isn’t lowered you can almost get under to change the oil without raising although its better to get it higher for some elbow room.
Is it worth putting the car up on 4 axle stands so that it’s level? And to check the pop level of the gearbox is it just get it flat and once it’s started spilling out it’s fine?
Probably easier to get it up on 4 stands, I like it on just 2 on the one side then I’ve got at least 2 wheels on the ground.
Above all make sure its solid on the axle stands before attempting to go underneath.
I’m getting beyond all this stuff now but when younger I’d love a challenge like changing oils myself.
If you haven’t got the proper tools just buy the oil washers and find a friendly garage to do the job for you, it shouldn’t take them long, definitely not as long as DIY.
Just ensure the refill nuts are fully removable before your drain nuts for Pete’s sakes.
Nothing worse than a man getting into bother because of his nuts.
I am young and love the sound of doing this! I know I’ll hate it once I’ve started but it’ll save me (some) money and I have the time so why the hell not?!? Thank you for all the advice!
Once you do it, you will very likely become reluctant to part with hard earned for someone else to do it in future…plus a few other easy peasy wee jobs.
Good man.
I jack the car up and place a concrete block under each wheel.
I also place a piece of scaffold board cut to size on top of that.
Then lower the car, (wheels on obviously) back down, hand brake on and wheels chocked.
That will give you sufficient room and will also be level to carry out the job nice and safe.
You can do the gearbox, engine oil/filter this way too.
I never really like going under a car on axle stands.
Good luck and just take your time.
Hi just serviced my nd. Up on four stands, I like to keep the car level on oil changes. Always serviced my cars myself, I know it’s been done properly then. Once up give the car a good shake to make sure it’s safe, blocks under wheels sounds good advice if your not sure. You sound youngish me I’m 73 & still get a buzz messing under cars. Good luck & have a go.
This is a great blog that detailed exactly what you need and do to service you MX5. This and the Haynes manual for the torque settings etc. got me through doing a service.
Then you’ll have plenty for future years and some varied sizes for other cars and projects.
OH! Get something like this if you do not have one already. Assuming from your post you have never done a service before. I could not have done the diff and gearbox without it.
Lastly, it’s worth buying a torque wrench. See it as money saved not paying someone else to do the service this time and then money saved in future. It is especially important to get the torque right otherwise you could cause more harm than good for something less than £100 but would be useful in your toolbox forever, especially if you look after it and do not abuse. At the end of the day, if you are servicing it yourself to know it has been done right, why bodge the job in the first place?
Crush washers are washers made out of soft metals. Eg. Copper is a suitable material for a crush washer as it’s a malleable, and ductile metal ideal to fill the shape around the bolt perfectly for a liquid-tight seal. If you don’t believe me then pay a premium for someone to rename an aluminum/copper washer a “Crush washer”…
You need more torque to seat a copper washer than an aluminium one. That is why you use aluminium to stop you over tightening and therefore avoiding stripping the thread.
I use aluminium.
Are the washers linked to in @Smiiffy’s first post suitable? They are described as ‘crush’ washers, so does that mean that they are made of softened copper, or is any form of copper not suitable?
