I change my oil when it is hot, normal running temperature. However, I modified my Topsider by removing all but a small section of the Tygon tubing. I left just enough to connect the nylon PVC line to the metal cap, so about and inch and used two tie wraps to secure both. The tube get warm but not too hot to touch. This has been working very well for me for all my vehicles and I have been getting 100% extraction. Regarding the concern of sludge remaining in the pan I am not too worried ; this summer I dropped the pan on my jeep to replace the main seal and there was a 1/4" lip around the oil plug that would prevent full drainage and there was hardly a film on the pan and that is with 80K miles! Considering I am using tier 1 gas and much better quality oil in the Crossfire then the Jeep I would greatly be surprised if sludge is going to be and issue, beside I change my oil every 4K-5K miles.