Changing auto trans fluid

[Auto]

Hi i though i had better change the auto transmision fluid it looks a bit dark i dont think its been done for a while if ever
so my questions are
do i drain the fluid out by removing the dipstick tube ?
is dextron 2 ok to put in or is there a specific type ?
any tips most welcome
thanks phil

[syncrosimon]

I am sure the Haynes manual will tell you, but I seem to remember on mine that you unbolt the bottom of the gearbox sump, which drains the oil, then you have access to the wire mesh filter, which can then be cleaned. Top up through the tube, carefully, as very sensitive to low or high levels. iirc you have to check the oil level in gear or something like that, but not cold, and engine off.

I am sure someone will be along in a minute with a recent experience.

[Red Westie]

The valve block (the internal assembly that controls gear changing) is machined to ultra fine tollerances and is extremely susceptable to small particals within the oil jamming the valve operation.
You are indeed wise to change auto fluid when it shows signs of darkening as this is a prelude to possible auto change issues.
I cannot be specific to T25 but most Auto's either have a drain plug on the geabox sump or require the sump itself to be remove in order to drain and clean.
Once removed it is very important that all sediment is cleaned out with the minimum of disturbance including the filter.
Re-assemble, find the auto box capacity and correct fluid type, re-fill with 60% of stated capacity (down the dipstick tube) then fill and dip untill between min/max marks.
Checking should be done with the engine running!!!!! put your foot on the brake pedal and slowly work the gear lever through all positions, leaving it in each position for 2-3 seconds then return to P (park) engine still running, now check the level on the dipstick.
Keep topping up and running through this sequence until correct level is attained.
Fill to the middle of min/max when warm as it will rise higher when hot.
Martin

[Bosun20]

I`ve just done this on mine.
You drain the oil with the dipstick tube nut that goes on the sump.
I had to warm this up first to get it to undo. Used a small gas torch.
You can then remove the four bolts holding the sump.
There is a gauze filter inside that needs cleaning out or replacing depending on condition.
There`s a rubber seal on the sump that should be OK to re-use.
But i got the gauze and gasket from VW before i did the job.
If you get a Haynes book it does tell you the oil spec, amount and how to do the job.It is easy to do.

[Auto]

Thanks for the tips every one i'll be ordering the parts for the job asap
thanks again all the best phil

[caveman]

Just be warned that changing the atf on a transmission which has never had it changed before may cause your trans to fail. New ATF has lots of detergents and when they work there way behind old hardened seals, clutches and brakes they sometimes clean away all the gunk -which was keeping everything working. I worked across the street from a transmission specialist for 20 years [they have 50 years experience] and they got to the point of refusing to change ATF for the sake of it. More than half the time after changing the fluid, the car would get down to the end of the street and then it would start slipping between gears or fail completely. Remember that trans oil doesn't get contaminated like motor oil. If the oil is bad [smelly and very dark or black] then the transmission is probably on it's way out anyways.If your transmission is working fine and the oil still has some red in it and it doesn't smell burnt , i would leave it alone.

[kimbobill]

Just be warned that changing the atf on a transmission which has never had it changed before may cause your trans to fail. New ATF has lots of detergents and when they work there way behind old hardened seals, clutches and brakes they sometimes clean away all the gunk -which was keeping everything working. I worked across the street from a transmission specialist for 20 years [they have 50 years experience] and they got to the point of refusing to change ATF for the sake of it. More than half the time after changing the fluid, the car would get down to the end of the street and then it would start slipping between gears or fail completely. Remember that trans oil doesn't get contaminated like motor oil. If the oil is bad [smelly and very dark or black] then the transmission is probably on it's way out anyways.If your transmission is working fine and the oil still has some red in it and it doesn't smell burnt , i would leave it alone.

really Good post Caveman,

colour shows you the condition of the box, had to have mine reconditioned 5 years ago now, still a really nice red colour and uses very very little.

[caveman]

That's the thing, you can't really determine by the color. I've seen lots of cars where the oil was dark, but worked fine. The rule is that if since new the oil was changed regularly, then keep changing it. But if you don't know or if it has more than a 4-5 years and more than about 60,000 mi leave it alone. If the oil is bad, it's too late anyways.

[Auto]

Hi now youve got me worried the oil has no red in it at all its more the colour of engine oil when its new a sort of a golden colour but no smell of burning
the box its self works fine very smooth i just want it to last me i havent had it too long and not really been camping in it yet
Has any one else had there auto box fail after an oil change or can any one any advise on what i should do now ?

[caveman]

Okay i wouldn't worry about the color .Some atf is clear i.e. the newer vw ATF is clear/light brown. Someone must have changed it already. If it's like you say- like almost new motor oil and it doesn't smell, i recommend you leave it alone.