Gearbox oil

marty085 · Postby **marty085** » Fri Sep 12, 2014 5:33 pm

I had Royal Purple in an old NA. Crunched like hell and I swapped it out as soon as I could. Replaced it with MT-90 and it shifted like a hot knife through butter.

pie5 · Postby **pie5** » Fri Sep 12, 2014 7:59 pm

It's been six weeks since I put the the Ford Spec WSD-M2C200-C 75W-90 GL4 Gear Oil in my car and I'm very happy with the shift feel.
Nothing negative to report so far and it's much better cold than before and even better once the box has warmed up.

khlmx5 · Postby **khlmx5** » Sat Sep 20, 2014 3:42 pm

Hi, is it standard requirement to change oil under the shift stick? Or only oil change from under the car is sufficient?

gslender · Postby **gslender** » Sat Sep 20, 2014 10:57 pm

Change both, but obviously the oil in the gear case gets more abuse than the oil designed to lube the linkages.

greenltd · Postby **greenltd** » Sun Sep 28, 2014 10:25 pm

I changed my gearbox oil today in my NA 5 speed, and found that the shifter turret was empty, just like the last time I changed it. There is no obvious leak at the rear of the box. Does anyone know if the shifter oil can work its way back into the main part of the box?

hks_kansei · Postby **hks_kansei** » Mon Sep 29, 2014 8:07 am

greenltd wrote:I changed my gearbox oil today in my NA 5 speed, and found that the shifter turret was empty, just like the last time I changed it. There is no obvious leak at the rear of the box. Does anyone know if the shifter oil can work its way back into the main part of the box?

it can work back to the box, but it shouldn't.

The selector rods have seals around them to prevent this happening, but over time they can wear and eventually will let the oil pass through into the main gearbox.

pezchops · Postby **pezchops** » Mon Sep 29, 2014 9:40 am

i don't know what oil i had in my box or how old it was but it didn't look like MT-90.
when i recently changed it with MT-90 there was no notable difference in gear change hot or cold.
there is the placebo effect knowing i used the more expensive and popular brand out there.

perhaps anyone that uses an `in spec gear oil' and feels a big difference had changed out really old oil or there was not enough/too much oil in the box.
forum feed back is mostly just peoples opinions be it informed or not.and generally not having scientifically proven data.
so in the end you just need to make your own choice of oil but at least `stick to spec'.

next time i will try a less expensive `in spec gear oil'

Mr Morlock · Postby **Mr Morlock** » Mon Sep 29, 2014 10:22 am

I think placebo affects are alive and well. Gearbox oil is not exactly one of the things that wears out quick on cars- look at the service changes on nearly all cars- long. Provided one uses a well known oil and in line with service it should be ok.

gslender · Postby **gslender** » Mon Sep 29, 2014 2:21 pm

Mr Morlock wrote:I think placebo affects are alive and well. Gearbox oil is not exactly one of the things that wears out quick on cars- look at the service changes on nearly all cars- long. Provided one uses a well known oil and in line with service it should be ok.

Not all owners of mx5s drive like old farts and service schedules are guidance, not a way to live your life by. But hey, what's the point in telling someone like you this.... You've become concrete in your ways....!

manga_blue · Postby **manga_blue** » Mon Sep 29, 2014 2:42 pm

Morlock has never experienced the impacts that different oils have on our gearboxes. I've tried 5 or 6 different oils across 4 gearboxes. The only things I can clearly say are that there are significant differences in shift feel between different oils and that each individual gearbox responds differently to different oils.

Only one oil (Syntrans) has been disastrously bad and only one oil (Redline MT90) has been consistently good enough to suit my own (rather extreme) purposes. All the other synthetic oils that I've tried are good enough to give good shift feel in a daily driver, so I'd just be dríven by price in that case. I wouldn't bother going mineral, simply because of cost and labour savings in the extended life of synthetics.

The American · Postby **The American** » Mon Sep 29, 2014 6:33 pm

My last car was an NA with a smooth shifting 5 speed and standard shifter. I used a higher grade Castrol product in that car which also improved it. Current car is NB 6 speed, and an IL Motorsport short shifter. With unknown oil, the shift was far from smooth when cold, and not as nice as the 5 speed at any time. I switched to Redline MT90, but have not felt much improvement. I'm now thinking about reinstalling the standard shifter to see if I can slow the shifts down a bit with the longer throw and reduced shift effort. Or I might try the Castrol product. I'd be happy to try snake oil if anyone has any suitable for synchro.

greenltd · Postby **greenltd** » Mon Sep 29, 2014 8:41 pm

Its funny really. Not long after getting my NA I changed the gearbox oil and filled the empty turret with Burson's branded gl4 oil. Shift action was way better when cold and less notchy at all times. Then my mechanic had to pull the box out and ended up changing the oil a second time. He says he used the same Hudson's oil, but I'm not sure. The gear action felt like it was back to its old self. So Sunday I changed it again to Castro, and found the turret once again empty. Today the action was definitely way better when cold, and a little better warm. I suspect much of my issue may lie in the turret loosing oil back to the box proper. So far happy with the Castrol, time will tell.

khlmx5 · Postby **khlmx5** » Mon Sep 29, 2014 10:08 pm

So where did the oil go from the turret? Also, do u , as easy as just fill out the turret box?

greenltd · Postby **greenltd** » Tue Sep 30, 2014 9:33 pm

I'm guessing turret oil leaked back into the box, but possibly only when being used. When I left it overnight, there was no noticeable drop in turret oil. When I fill, I fill the box with its filler, and obviously the turret from the top. After two days driving, the shift is notchy again, although the general action good. I'll check the turret again this weekend........