If you have a car you have trouble burping the cooling system, hit buy now. We have a 2006 Subaru Outback LL Bean which has the six cylinder boxer engine. They are notoriously hard to burp when you change the coolant and thermostat. Reading on the forums they recommended one of these. We did the flush and put the coolant and water back in. Hint, put the front of the car up on ramps if you have them. Tilting the car upward helps. The benefit of the funnel is, not only makes it easier to pour in the content, but also gives you water surface to watch for bubbles. It also prevents the system from pulling air back in. The Outback we had a terrible time getting it to belch. The car would heat up, the fans would start screaming and I would turn it off and let it sit a few minutes. Did this about three times. Clue that it's not working, the lower radiator hose stays cool. I then finally started the engine and run the RPM's about 2500 for a few minutes and I saw a bunch of bubbles and steam, and felt the radiator hose which was now hot. The Thermostat had opened and let the air pass. We let it run another ten minutes watching for the dreaded head gasket bubbles but soon all the bubbling stopped and the car stayed right at 185 degrees idling with the AC on. Unfortunately the car still heats up when you drive it fast. Not sure what is going on.