i would like to use a Vacuum pump to suction as much transmission fluid out of my 2007 Tahoe. I have used the pump on other vehicles to drain oil out etc. I know this is not the by the book approach but changing 50% of the oil is better than changing 0%. Is the dipstick on the 07 Tahoe fairly straight. If the dipstick is not a straight shot it is hard to get the suction line into the pan. Also, is it a must to change the filter? I am not maintenance schedule averse but i hate to take my vehicle to the shop if i can do it myself

 

Its not that much harder to just change it.
Doesn't do you much good just to change half of it.

 

The down side to this is besides leaving a lot of used tranny fluid (which happens when you drop the pan as a lot stays behind in the torque convertor) is you aren't changing the filter.

 

I would have to second that.. yes you are trying to do good by replacing the fluid , however once the engine stops the suspended particles in the fluid sink out of the fluid and in to the pan where the filter will deal with them next start up. So not only replace the fluid and the filter but remember to clean the pan, many have a piece of sheet magnet in the bottom of the pan that looks like its covered in a clay or sludge..well it is, its the fine particles of metal ground so fine from the normal ware of the gears and clutches.