ive got 137k on my 03 c32 ,so Im going to replace the fluid and filter. No issues with the tranny,works perfectly. Ive got the filter, fuchs 4134 fluid and the shop dip stick. Question is ,do I check the fluid level hot or cold,in "park" or in gear ? thanks

Hello, you check the transmission fluid level with the vehicle in park and the engine running. When you just do the pan and filter change on the transmission it's just under 4 liters of oil you need to replenish. You also can check it hot or cold.. the dipstick has markings on it for 40 degrees and 80. After you replace the filter just add 3 liters and start the engine wait a few minutes for it to travel down the tube as its deceptive; and then start checking and correcting the level with the dipstick.
Little bit of advice as well, replace the transmission pilot bushing while you are doing the service as well, this part leaks on all the transmissions.

When you check the level warm it has to be 80 degrees C. I used an infrared temp gauge to check pan temp. I had to put it in D and rev to 1100 rpm to get it to temp, other foot on the brakes. Hard driving got me to 70 maximum.