Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

2003 gmc oil in radiator

I have 2004 GMC sierra with 125k miles. It recently started smoking when it’s cold and stops once warm. It also had a low coolant light twice in the last month. (Just started smoking a few days ago) u changed the oil and added coolant yesterday and oil looked fine no milky, but radiator fluid had a reddish tent and looked like it had oil mixed with it. What could the problem be?

Well, white smoke at cold start up is normal in cool weather and does stop when it is warmed up.

Its a GM vehicle which means that the coolant, unless you’ve changed it out, is probably DexCool which is orange. I’m not sure if that could be read as “reddish tint”.

However, if this is an automatic transmission then that reddish tint could very well be transmission fluid. Your transmission cooler lines probably run through your radiator and if there is a leak there, then you might have coolant and transmission fluid mixing. This is VERY BAD for the transmission. I’d suggest that you check the transmission fluid immediately. If it looks like anything other than nice, clean, red fluid then it may be too late for the transmission.

Of course, if it is a manual then I don’t think that’s a concern.

Either way - you apparently have a coolant leak to identify.

The transmission oil cooler, located inside the radiator, could be leaking ATF into the radiator…What does the transmission dip-stick look like? Also, a blown head gasket will produce these symptoms…