I just look at a 97 SSEi and it had a lot of brown stickey stuff it the top half of the tank stuck to the sides, This is the second one with the same stuff I have seen in the last two days, Can any tell me about it, I see a lot of info on water getting into the oil,But is the oil getting in to the water tank??? Help I would like to buy this last one if it not some thing real BAD, Thanks for and help or info. Dennis

it'* probably just a buildup of gunk after a period of time. It probably needs a cooling system flush.. (the coolant should be orange I think they started using DEX-COOL in 1997...)

Actually, that gunky build-up in the overflow tank is probably the remnants of original factory installed sealer that was integrated into many GM car. It was/is made by BARS that also makes those sealant tablets GM suggests using in most owners manuals. Not sure if it was used also with sytems requiring DEX-COOL though....

It'* a bitch to flush completely from your cooling sytem, by the way, so a thorough professional flush might be a consideration if you're not prepared to spend a lot of time flushing the sytem out yourself.

If you want to clean out the overflow tank really good, after flushing it out with water a few times, get a coat hanger and wrap a small piece of old wash cloth or towel to the end with a strong elastic band - this way you can bend the hanger in different directions to losen and wipe away the build up on the top insides of the bottle. Than just keep running water in and through the bottle so it flushes the gunk from the hose that connects to the overflow tank hose to the radiator.

I found the same thing in my 96 SSEI a couple of years ago and did the same as anthony. Put the overflow bottle in the kitchen sink & cleaned it out with a coathanger with papertowel on the end & Mr. Clean. I was told that the brown stuff is from the pellets that the dealer sells & that they are organic & work with dex cool. No leaks or brown stuff since.