300D transmission fluid change... must it be warm?

[landev]

Greetings,

I've finally gotten the time to pursue changing the transmission fluid on my '96 E300 and found the step-by-step on this site inspiring and easy to follow. After 202K miles, I think it's probably time.

The issue I've run up against is that of a warm transmission. I.e. I did as instructed, warmed up the car, took a bath in fluid, then changed the filter which came in a Meisterstadt kit. All was fine and dandy until I realized that the seal for the pan does not fit this car.

I looked at the second kit which I purchased to do my '84 300dt... the filter is different, but the seal is the same. In short, I think the packaging somehow got bollixed up and now I'm awaiting a new seal.

My question is this: How imperative is it that the transmission be warm when introducing new fluid? I could put a magnetic block heater on the pan to heat things up a bit once there's some fluid in the system, but I'm curious... Why does the transmission need to be warm, or is that only for the drain?

Any ideas would be appreciated!

Thanks much in advance!

-l-

[Govert]

A warm drain is recommended because the oil flows more easily and any dirt and contaminants are suspended in the oil. I never read or heard that the transmission (or engine or other oil containing part) needs to be warm for filling.

[Skippy]

It generally doesn't need to be warm for filling. The only hiccup is when you're working on something newer and odd like the last few years of Audi and VW autos, where the final fill requires a scan tool and having the transmission oil in a certain temperature range in order to get the level just right.

[vstech]

it's impossible to have the transmission warm for filling, unless you are REALLY fast at draining, and that kinda defeats the purpose of extended draining to get it all out.

you want to drain hot, right after a long drive,
let it drain completely, including the torque converter drain!!!
replace the filter, change the gasket, reassemble, and fill with the 4 or so quarts, start the car, let it idle a bit, then fill to the low line, and go for a drive. park on PERFECTLY LEVEL GROUND, and adjust level to the full mark, only when the transmission is completely warmed up!

[landev]

Indeed it seemed likely only for a warm drain... not warm fill, but new transmissions are out of my price range, so wanted to make sure.

Thanks much!

-l-