kind of antifreeze?

Hello,

Look at the color make sure it is the red stuff as that what the factory would have put in. If it is red (orange) then the Dexcool is what you want. You should get 2 gallons and top off with water. Here is a video top help you see how to do the job.

https://youtu.be/j8_MD76LbiQ

and

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

and

https://www.2carpros.com/articles/engine-coolant-59420607

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken

2003 Chevy Silverado V8 Two Wheel Drive Automatic 104000 miles
----------------------------------------------------------------
What kind of coolant should i use? does it matter what color it is? and should i flush out the old coolant completely?

your vehicle takes gm dexcool. ive worked for gm for 10 years. if your coolant is brown id flush the system and put the old green antifreeze in it. the dexcool is supposed to last for 100k miles but unfortunately in my opinion is very poor quality.