Classic cars forum & vehicle restoration.

[baconsdozen]

I've heard conflicting reports as to wether changing automatic gearbox oil is a good or bad idea.Some say the change is pointless unless the box is stripped as it stirs up more rubbish than it removes,others that old fluid alters in viscosity and is thus worn out.
Any thoughts ?.
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Thirty years selling imperial hand tools for old machinery(Now happily retired).

[47p2]

Old ATF is full of swarf water and other contaminants. Best to change it sooner rather than later.

If you are draining it out of the sump I don't see how it can stir up any rubbish
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ROVER
One of Britain's Fine Cars

[mid]

my daily driver (98 BMW 5 series) has a so called 'sealed for life' gear box...even BMW suggest changing the oil and filters before 100k miles and then more regularly afterwards.

[47Jag]

Mid,

The problem with BMWs is that the dealer has to do it. There's no filler tube and I think it's a plug on the side of the gearbox. I got an E34 done about 10 years ago after a cooler leak. I think they charge about 1/2 hour labour plus materials.

Art

[michael1703]

you cant drain all the oil out of an automatic, the torque converter will keep its oil unless you physically removed it and drained it

the torque converter will be where the swarf collects

btw.... if you get near mendlesham way i can sell you some new stuff cheap, ive got gallons of the stuff

[47p2]

If you drain the oil from the sump then remove the king lead from the distributor and turn the engine over for 10 seconds you will remove most of what is in the torque convertor
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ROVER
One of Britain's Fine Cars

[baconsdozen]

Thanks for the replies.I drained the box (it was pretty grotty the stuff that came out) then filled it and did the same thing again after a few days.The box is supposed to hold about a gallon but I could only get about half that out each time.
I still have the tails of dirt being disturbed and blocking oil ways ringing in my ears but (touch wood) apart from one reluctant gear change when I first filled it,its been OK.
_________________
Thirty years selling imperial hand tools for old machinery(Now happily retired).

[P3steve]

I still have the tails of dirt being disturbed and blocking oil ways ringing in my ears but (touch wood) apart from one reluctant gear change when I first filled it,its been OK.

The reluctant gear change was most likely just the fluid flushing out any air bubbles in the valve chest where you had drained it. Steve

[baconsdozen]

Just realised I can't even spell "tales".
I think you're right Steve,since then the gearbox has performed well,it seems to work a bit better than with the old grubby fluid.
_________________
Thirty years selling imperial hand tools for old machinery(Now happily retired).