4200 Gearbox Oil Change - What Oil?

Evo Cymru

Member
Messages
625
Opie oils recommended Motul one for me as well so have used it for past 8 years (can’t believe it’s that many years now!?) without any problems...

yet!
 

TimR

Member
Messages
1,688
According to Tim @OpieOils...

See here, an extract from the Lamborghini forum (found here https://www.pistonheads.com/gassing/topic.asp?h=0&f=68&t=1752379) where he offers an insight into the Rotra LSX...(It's for tractors...lol)


The synchros in a gearbox want a GL4 oil, but the diff wants a GL5 as the GL4 level of additives help to slow the synchros for changes. The diff wants the GL5 level of pressure additives to protect due to the high pressure generated in the diff.

I spoke to one of the oil companies a while ago about the Rotra LSX as it was something I hadn't heard of and when I was searching for it, it was listing commercial vehicles. It turns out that the Rotra LSX is primarily aimed at heavy off road vehicles, like the big dumper trucks used in quarries, rather than high performance cars.

The two oils I would look at using are the Motul Gear 300 or Red Line 75w-90NS (rather than the MT90 as it is a GL5, but aimed at gearbox use). Those two oils are very well proven in Porsche and Ferraris, where the oil is shared between the gearbox and diff. There are a couple of Gallardos I can think of that use it as well.

https://www.opieoils.co.uk/p-899-motul-gear-300-75...
https://www.opieoils.co.uk/p-1017-red-line-synthet...

In most cases, they work fine and do not need any additional friction modifier, but if your diff is noisy, I suspect it will need the modifier and the Red Line one is ideal.

https://www.opieoils.co.uk/p-6320-red-line-limited...

You need to be careful with the friction modifier, too much will lead to the diff slipping more than you want and it will prevent the synchros from slowing enough, leading to poor changes. Too little modifier and it will still be noisy and the diff too keen to lock up. I would add it a quarter of a bottle at a time, then take the car out and test it, so you will find the correct level. That's basically how the Pakelo stuff would work (although I have no idea about their oils, we don't get them over here to my knowledge).
 

tulit

Junior Member
Messages
70
Yup. I personally don't believe a straight up GL4 is a good choice. You need to find a GL5 that is mainly yellow metal safe. The redline (maybe hard to find in the UK?) and the Motul seem to fit the bill.

Sent from my SM-A515W using Tapatalk
 

Eightpot

New Member
Messages
1
Update: this is an awful job and if it goes wrong (i.e. the filter breaks apart) can take ages. I ended up drilling mine out, had to buy a bunch of hole making drills and all sorts of tools. I am all for DIY but this is one I wished I had taken to an indy. If I ever tackle this job again, I might have tried something like a corkscrew into the filter.
 

conaero

Forum Owner
Messages
31,230
One other little tip, it the filter breaks or separates in two, you can go up the drain hole with a pic tool and push it from behind.