Hello folks. I'm having a little problem extracting most of the oil out of my newly acquired '86 300SDL via dipstick. I'm using a Topsider that I've had no problems using on my other car, an '85 300D. The Topsider's got vacuum and works as it should. I'm only getting roughly 6 liters out of the SDL. I have both the oil filter and oil filler caps unseated. The car, warmed to operating temps, is parked on a slight slope with nose downwards. I'm wondering if either the oil pan's construction or the dipstick tube is preventing the Topsider from doing a better job. Any help is appreciated.