NC gearbox oil recommendations?

emilmh · Postby **emilmh** » Tue Oct 17, 2017 8:02 pm

The NC manual recommends 2.1l of GL-4 75W-90 for manual transmission.

I have heard that GL4 gives better results than GL5. (According to my mx5 miata forum research, with NCs being 10 years old and having some kms on them the synchros work better with GL4)

I am having trouble finding something suitable from super cheap auto or repco. US sites recommend oils that are too hard or expensive to find here so I was hoping for some Australian based advise.

I was going to go with Penrite Pro Gear 75w-85 because it is synthetic and NOT GL5, but it is rated a bit below the 75w-90, and it is also GL-4 "plus" (whatever the plus mean) so I'm not sure what's other alternatives are easily available.

Any suggestions?
Thanks in advance.

Mr Morlock · Postby **Mr Morlock** » Tue Oct 17, 2017 8:29 pm

Apart from other experts here you can ask oil suppliers e.g. ones that actually really know something about the products- I dont think the average staff at SCA have the training or the knowledge. You can also talk to the information guys working for oil companies- while they will recommend their own products they can at least discuss and recommend alternates. My guess is that if you follow the spec recommended it will be ok. There are a lot of stuffed gearboxes around because many just abuse their cars not because the oil was a problem.

JBT · Postby **JBT** » Tue Oct 17, 2017 9:10 pm

I'm using this. http://www.nulon.com.au/products/gear-and-differential-oils/full-synthetic-75w-85-smooth-shift-manual-gearbox-and-transaxle-oil Smooth shifts (including 2nd gear from 3rd or 4th) cold and hot. Most impressed.

The Penrite stuff I tried wasn't as good.

Regie · Postby **Regie** » Wed Oct 18, 2017 7:59 pm

^^^ yep as above I'm using the Nulon GL4 stuff, awesome oil. The closest you will get to the famed Motorcraft oil the Americans rave about over there

emilmh · Postby **emilmh** » Wed Oct 18, 2017 8:40 pm

JBT wrote:I'm using this. http://www.nulon.com.au/products/gear-and-differential-oils/full-synthetic-75w-85-smooth-shift-manual-gearbox-and-transaxle-oil Smooth shifts (including 2nd gear from 3rd or 4th) cold and hot. Most impressed.

The Penrite stuff I tried wasn't as good.

Can you remember if the penrite you tried was the synthetic "Pro Gear" or just the regular stuff?
I checkout out supercheap and they don't seem to have that Nulon oil. It's a shame australian retailers have such limited range in stock (even when the brands are Australian!)

Mr Morlock · Postby **Mr Morlock** » Wed Oct 18, 2017 9:31 pm

I am an eternal sceptic- the famed magic potions- rub it on your skin and the lines go away. My local oil supplier actually knows the products- not just for cars but recommendations for equipment as well- SCA etc just sell oil in a package at a price and would not have a clue about the ingredients.You dont need 100 choices.
It was not all that long ago that I had some oil removed from a gearbox because it was put in an older vehicle and the modern oils could have caused a problem- not worth the risk- it was drained and replaced at no charge to me.That same vehicle also uses old style engine oil- I would not put that oil in my MX5. Oils are not necessarily better because they are synthetic- it depends on the application. Car Cos recommend Specs not brands. Incidentally- its not recommended to rush changes when the oil is cold- its a poor way of driving a car- if you mask a symptom it can lead to damage. Athletes often warm up / stretch before an event.

JBT · Postby **JBT** » Wed Oct 18, 2017 9:54 pm

emilmh wrote:Can you remember if the penrite you tried was the synthetic "Pro Gear" or just the regular stuff?
I checkout out supercheap and they don't seem to have that Nulon oil. It's a shame australian retailers have such limited range in stock (even when the brands are Australian!)

I think it was Trans Gear. I don't think Pro Gear existed then or I would have tried it.

I thought I bought the Nulon at SCA but maybe it was Repco.