It will syphon back a couple of inches out of the filter, if you let it sit an hour or so before you pull the plug & drain it. Once you drain it, it will not syphon any more from the filter. During that hour, it will also allow the quart of oil in the injector pump, (12v engines, see owner's manual) to drain back to the pan too. They don't wait that long at WalMart or Jiffy-Lube.