My gearbox used to slip a while back. Checked oil and was *black* so got it flushed and changed, filter changed, and an additive to try and soften the seals/o-rings. Since then it's stopped and come good again until the other day.

For some reason while it's underload it's fine, and if I thrash it it doesn't slip. Yet as soon as I'm cruising along at the speed limit it slips out and free-revs until it picks up again at about 5000rpm

I'm thinking that because it doesn't slip while under load that it probably (hopefully) isn't the bands. Could it be the torque converter playing up somehow? I've checked the oil and it's nice and clean and red so it's not that this time.

Cheers guys

Do the diagnostic and check for fault codes, otherwise check the oil level again. It need to be done warm and with the engine running (assuming you have a dip stick) otherwise cold and so it is just starting to come out the filler plug.

Is there a link somewhere for how to do the diagnostic on it?

I've checked the oil while it was warm and idling away in Park and the level is fine, sits at the top of the marks.

Look in the technical documents for the info on checking the codes. How's your oil looking? If it was iin such bad condition last time, maybe there's still gunk and what not in the box and it's deteriorating quicker thanit should be. Or maybe your box is damaged from bad maiintence or is just generally old and worn.

I couldn't find anything in the technical documents about gearboxes apart from some stuff on oil...

The oil is nice and clear and red, instead of dark brown/black like it was when it was slipping last time. Last time the box got flushed instead of just having the oil drained and replaced. My mate who owns the place did it and said he used like 20L of oil to flush it properly and get it all nice and clear again, and said that my filter was black and knackered. That was done in June so it shouldn't be the oil already.

It could well be that it's just an old, tired gearbox too... the bloke who had it before me was always towing horsefloats (he's a C**k) and his trailer around (electrician) so it would've had a hard life. I have access to an EL gearbox, but I don't want to have to bother swapping them if I don't need to and if there might be a cheaper fix for it.

How much should a 2nd-hand box set me back? Probably looking at around the $300 mark, yeah?

could be the solonoid playing up, from what i remember it's the vp5 solonoid in the auto...my EA was doing the same thing...now it's dead, so watch out

the solonoid is about $500 to fix, a second hand auto, non-recon (so could be in any condition, might die a week after you get it) will set you back about $300 - $500...a recon will be between about $800 - $1400.

Yeah I can get an EL XR6 box that's done low km for about 300 clams if needed. Looks like it might be my best option at this stage...