I have a real wierd one. The 560sel sat for 2 weeks in the garage not started or driven until two Sundays ago. It was very hot and muggy at 6 AM. I went into the garage and found a 3 foot puddle of antifreeze on the ground and saw the drip drip drip from the front of the car. I raised the hood and noticed the bottom of the rad above the bottom tank on the driver's side had antifreeze on it where the tubes join into the aluminum - i had lost about 1 1/2 quarts of antifreeze and in about 5 minutes there was about 1/2 inch in the margarine cantainer I had put under the car. I started the car and drove it out of the garage to clean up the mess. I then drove the car back in and let it sit for the last two weeks - believe it or not - NO LEAKS!! Yesterday I pulled the rad and blew it clean with an air gun. It was still a little damp where the vertical tubes go into the aluminum at the bottom driver's side. After I blew the rad clean and made sure it was totally dry - I filled it with fresh water after plugging the hole for the lower rad hose and the hole for the hose from the overflow tank. I let it sit for an hour - no leaks. I then pressurized the rad for 10 -15 minutes - absolutely NOTHING - NO LEAKS. This has me baffled - but after having 1 1 /2 quarts drip out - I don't trust the rad. - and YES - it was the rad leaking - not a hose and not the water pump. Since problems don't cure themselves and this rad still looks like new - I don't want to spring for a new one. Auto parts stores sell something that is a little blue gray jar with black round things in it with a liquid to stop leaks - can't remember the name of the manufacturer - but it begins with B. The jar says it is used by the Big 3 from the factory to prevent leaks. Should I put this stuff in to give me a comfort zone? Any other ideas - I don't want to be on the road and have this happen again. I notice that others on this site say to use pepper - but......... Any other ideas other than a new rad? Strange things really do happen in real life!!!