Gearbox oil colour

[Dot]

G was doing some checking of oils, water etc in the bus and got a bit of oil from the gear box. The oil came out brown he put the oil in a bottle and after an hour or two changed to black . Is this normal or ??

[BruceS]

mmm, someone filled it with old engine oil over on the block? lol.
Had the bus been sitting overnight before he checked it?
Did the specimen come out of the drain plug?
Rubbing between his fingers was it pretty thick & slimey?
What is the recommended oil for THAT gearbox?

[Dot]

mmm, someone filled it with old engine oil over on the block? lol.
Had the bus been sitting overnight before he checked it?
Did the specimen come out of the drain plug?
Rubbing between his fingers was it pretty thick & slimey?
What is the recommended oil for THAT gearbox?

Was that someone you?
Bus had not been driven for 3 days. The oil recommended for the bus is Castrol 80/90 Right now the oil is being drained so shall see.

[T1 Terry]

You should have driven the bus till the gearbox felt warm to the touch before draining it, but too late now eh Is there shiny metallic fleck through the oil, lumps of metal on the magnet drain plug? Some shiny stuff and a build up of sludge on the magnet is normal, lumps on the magnet mean serious issues are about to come your way.
If there is a brass/gold fleck through the oil, you will immediately deny there was any because that shows you have been hammering the synro rings rather than speed matching the gear changes
Dark to black oil generally means you needed to change the oil a few hundred kms ago. If there are no nasty bits in it, after the next trip, drop the oil again while the gearbox is warm to hot, just after you return from a good solid drive, so the rubbish is still suspened in the oil and can be flushed out with the oil.
Modern oil has 3 jobs, lubricate and clean, then hold the rubbish in suspension. If the drain periods are too far apart, the ability to hold the rubbish is compromised and everything inside gets coated in the garbage. When a motor or gearbox is stripped down it is immediately obvious if the servicing routine has been kept up. Everything is clean, or there is a big cleaning job to do before anything else can be attended to, guess which one is which

T1 Terry

[Dot]

Thanks Terry, will do as told and will now pass this onto the little fella.

[Mrcoolabah1au]

The little fella leprechaun