Just curious, I never used a pump before to extract used motor oil and I don't know if I read what you were saying correctly.I just did my first oil change on my 3.6 and it is a cartridge filter. I had
a 4 cylinder Terrain which i traded for the jeep and it also had a cartridge
filter on the top of the engine. A lot of the Terrain owners on the Terrain
forum use a vacuum pump called Mity Vac. It uses tubing which you insert
down the dipstick tube, pump the device 3 or 4 times and it draws the oil
out. I was concerned about it getting all the oil so i marked the pump at
the 6 qt. level and thats where it stopped. It's a lot easier than using ramps
or jack stands. It took about 10 mins. to do. It's a little pricey at a little
over a hundred, but over time it will make changes a lot easier.
You were concerned that you would "not" get all the used oil so you marked at 6qrts and kept pumping till it stopped? or were you concern that it "would" get all the oil and so you stopped at 6qtrs?
I looked it up and it is $119 which is a bit pricey but if it means I dont have to lay on my old back and crawl to get the plug out...