Coolant has to be added to the vehicle often, whiloe no coolant leak has been observed (smell). No coolant spoted on driveway. oil inspection at oil change does not show tell tale (brown/milky) of oil leak through the head gasket. No funny smell or color exhaust fumes from the tail pipe. Where is the coolant going?
An extremely slow leak from the intake manifold gasket would not show up in the exhaust color, but it would still show he coolant level going down. A small external leak not visible fom the top of the engine would do so as well.
You need to have the coolong system PRESSURE tested, and I’m sure it will reveal the leak.
Yes, have it pressure tested. In addition to the small leaks suggested by Donick, an expansion/casting plug or the water pump could be leaking. It could be leaking from a number of other places too.
Your car is the right year and engine to be part of the Dexcool Settlement for a intake manifold gasket failure, but it’s past the date for any claim.
http://www.dexcoolsettlement.com/notice.pdf
I had the intake gasket replaced on my 2000 Blazer in 2004. Except for a slow drop in the overflow tank level there were no obvious signs of a leak. When my mechanic changed the oil there were only a few drops of coolant in the oil. The coolant displaces the oil on the main bearings which would lead to engine failure if the gasket was not replaced. He told me to take it to the dealership who confirmed that the manifold gasket had failed. It’s not something to ignore.
Ed B.
It might even be a leak at the heater. The heater has coolant in it all year long and if it leaks ine the summer it just comes out along with the condensation under the car. You might not notice it. How much are you loosing per units if time and miles?