Transmission fluid - drain hot or drain cold?

[///AlpinePower]

The only information given by the Bentley book is that hot transmission fluid can be permanently disfiguring. It seems like changing it while hot/warm would put it closer to the temperature range that the service manual states for checking proper fluid level.

[DeanP]

Change the fluid when warm. Avoid hot, because you almost always make a mess and it prevents you getting burned.

[///AlpinePower]

how crucial is the temperature range when changing the fluid? "Warm" seems to be within the range.

[DeanP]

You get more fluid to drain out. It also helps to loosen up any sludge or deposits so they will drain also. You just need to drive it a few miles to warm it up.

[BigTed00]

Change it fairly hot, just be sure to wear gloves. The drain plug doesnt start to leak until the last thread, so its no problem to remove the plug without getting fluid on yourself. If your really worried about it you could always use a wrench on the last turn and let the plug fall into the drain pan.

Also be sure to buy a quality pump for putting the new fluid in, those crappy little siphon pumps take way too much time and end up being a huge PITA.

On a side note, I hope your putting Royal Purple in there. That stuff is absolutly amazing! EVERYONE should run royal purple regaurdless of when their last transmission fluid change was

[DeanP]

Ditto the Royal Purple, it's good stuff.

[e36'n]

You know I put Royal Purple Synchromax in about 500km ago, and I'm not all that impressed. I'm not sure what the previous owner had in there, but I really haven't noticed a huge difference. I mean it's a bit smoother and by that I don't mean too much at all.

I drained mine warm, wasn't steaming at all.

How long is the tranny fluid supposed to last before the next change?

[BigTed00]

Maybe its due to the fact that I have a short-shift kit, but there is a very noticable difference in the smoothness of my shifts. Its nowhere near as notchy as it used to be.

[e36'n]

Yeah I have the 328/M3 short shift kit in my car as well. My only guess is that the previous owner had synthetic before.

[Riken]

Do you guys check the tranny fluild with the engine on or off? I think it is suppose to be ON otherwise the fluid comes flying out of the hole when you release the last thread. What is the proper way?

[UKFan4Sure!]

:eek:

I've read both.
One says to do it cold because everything has settled out into the pan.
Another says do it hot because it is thinner so everything drains out...
Go figure...

[UKFan4Sure!]

Do you guys drain the tranny fluild with the engine on or off? I think it is suppose to be ON otherwise the fluid comes flying out of the hole when you release the last thread. What is the proper way?

The ideas is to get it out, right? Drain it OFF.

[DeanP]

Is this car auto or stick?

[///AlpinePower]

yeah - forgot to mention this was an auto.

To make a long story short -
1. Drained fluid warm
2. Removed both sumps
3. Replaced filter
4. Reinstalled large sump with new gaskets and new bolts //edit: filled to top
5. Reinstalled small sump, filled with ATF, new gaskets, new bolts
6. Turned on car
7. Waited until sump temperature reached 110 degrees F (15-20 min)
8. Turned off car, Removed fill plug, Started car in Neutral
9. Filled to top with ATF again
10. Closed Sump
11. Test drive

There was a ton of shit in the transmission. The fluid was not badly discolored, but the magnet had a ton of crap on it. The filter looked thoroughly used.

[TboneM3]

Warm, like all fluids, ditto again on the Royal Purple :)

[UKFan4Sure!]

yeah - forgot to mention this was an auto.

To make a long story short -
1. Drained fluid warm
2. Removed both sumps
3. Replaced filter
4. Reinstalled large sump with new gaskets and new bolts
5. Reinstalled small sump, filled with ATF, new gaskets, new bolts
6. Turned on car
7. Waited until sump temperature reached 110 degrees F
8. Turned off car, Removed fill plug, Started car in Neutral
9. Filled with ATF again
10. Closed Sump
11. Test drive

There was a ton of shit in the transmission. The fluid was not badly discolored, but the magnet had a ton of crap on it. The filter looked thoroughly used.

At step 4, you did fill the large pan, too, right?

[///AlpinePower]

yep. sorry for the omission.

[atlantisvip]

I wanna add a little something I learned today .. To correctly do a tranny oil job, you also need to bleed the lines.. A bunch of oil stays in the lines even after dropping the pan (autos).. You wind up getting the new oil dirty quickly once it circulates from the cooler if you don't correctly bleed it all out...

[///AlpinePower]

I wanna add a little something I learned today .. To correctly do a tranny oil job, you also need to bleed the lines.. A bunch of oil stays in the lines even after dropping the pan (autos).. You wind up getting the new oil dirty quickly once it circulates from the cooler if you don't correctly bleed it all out...

The oil in the cooler is not worth going after. The new filter and clean magnet will take care of it. 98% of the oil came out from the sump.