Recently drained my coolant (1992 SE) but didn't get around to doing a good flush that I usually do...Filled with proper mix of quality coolant but when checking the inside of the radiator a day or two later I noticed a slight residue floating in the coolant and covering the inside of the radiator. It'* a little slimy to the touch and dissolves if you rub it between your fingers. A little collects around the rad cap too, but not that bad.

I recently had my car checked for the summer and no there are no leaks anywhere and also no sign of oil getting into the cooling system or coolant getting mixing with oil. There is no abnormal smoke coming from the exhaust, no loss of coolant, no coolant leaks, and no change in proper oil usage. So everything is in proper working order as far as I'm concerned.

It'* just a small amount of white residue (almost like small paricles of cotton) that makes the new coolant look a little hazy but does not see to effect the proper operation of the cooling system.

A mechanic down the street who worked for Cadillac and now works for Goodwrench told me that usually a good flush can get rid of the residue which usually occurs when mixing a brand that uses a silicate additive (which is still in the engine block) with one like the new Prestone "universal" type that doesn't use silicate additives (which I used recently when draining the radiator).

Anyone else ever see this before?

I haven't and I'm somewhat lax regarding mixing the regular and universal types.

I found out today that this white residue (had it checked) is simply a result of adding Bar'* cooling supplement last year - the 1992 Bonneville owners manual DOES state to add the GM coolant supplement or equivalent so I used it. Whatever additive is used in these tablets basically coats much of the cooling system. After a while though, depending on how many times the system is either flushed or drained, it eventually breaks free and just floats suspended in the coolant making it look hazy or dirty - especially the yellowish Prestone which is not as dark as most other green coolants. Other than that the entire cooling system is fine.

Anyway, I flushed the system out today and managed to get rid of most of that gunk. Still a little left but it'* too damn hot and not worth getting a stroke over.

Well, that'* good news!!!

Glad it worked out!

Thanks for reporting back to let us know what the white stuff was. Good to know.

Bars is brown. Could that have been just some leftover collant corrosion?