I never thought of that !

Recently while getting a new CV joint fitted the mechanic noticed that the little bit of oil that came from the gearbox/diff when he pulled out the drive shaft looked a bit dirty.
On further investigation, it turned out to be completely black and it was changed for fresh oil.
The mechanics advised that in motorhomes that often stand around for extended periods the gearbox/diff oil should be changed every 50k km or so as it becomes quickly contaminated by moisture and rust and other nasties which build up when the vehicle is not being used. He went on to explain that the period recommended for replacing gearbox/diff oil for vehicles in normal daily use is irrelevant when it comes to motorhomes.

My mh is 2005 with about 160k hardworking kilometers on the clock.

We sometimes read of people with gearbox issues, the above is probably a significant contributory factor.

My annual servicing regime includes a gearbox oil change, with the mandatory half litre overfill. A bit anal and overkill maybe?… I don’t think so in the scheme of things, it’s 27 years old and still going strong .

Up until a few years ago, my mh was serviced by either a FIAT main dealer or a mh dealer for the brand.
The job described in the OP was carried out by a transport operator with a garage specialising in servicing HGVs and other commercial vehicles, they are also agents for VB Air Suspension systems.
Considering the base vehicle used on mh's, perhaps such a garage is best for the mechanical side of servicing.

I believe the extra oil was to lubricate 5th gear which was an add on to vehicles up to around 1998 as it sits on top of the box

Didnt know about the extra oil thing, I had a driveshaft changed lately and the guy changed the gearbox oil. He didn't mention adding extra. How do you check it?

Pop the plug out on the long driveshaft side, let the level find itself and add 500ml extra. The extra allows the gear oil to flow over and flood the 5th gear which normally stays too dry if only filled to the normal level.



Mad Max is right, it was only the older 5 speed gearboxes that benefits from the additional oil adding.

@JJF Thanks for clearing that up,

Ok Jon im changing engine oil this week, ill have a look.

Is this any good Jon. Oil filter changed, slick 50 in and topped up with new oil, rarin to go.

Agh its upside down