I have a 99 mustang 3.8 and she runs great! I think I may have a leak but not 100% sure. It has 109350 on it. My rad is normly full but if I take it out and drive it it gets a lil low. I have no milky oil and not burning white smoke. I had my boss presser test it and passed and had new plugs put in not too long ago and they were clean and did not smell like burnt coolant.does not over heat and runs fine. I have also checked the weep hole and its all good. if I let the car sit for a few days and I take the cap off you can hear some of the coolant going back in the reserve if am I worrying for nothing ?? it has been this way for abt a yr and I have had no issues at all.