Aveos burp air well, but if it's going just over half it sounds like there could be a bit of trapped air. After topping up, did you idle it for 5 minutes or so with the overflow cap off, and the heater on full? I've never had to raise the front end up, but you could try that as well. AFA the coolant itself, concentrated used at full-strength should have the opposite effect. Just follow the directions on the container.