my 2005 chevy silverado 1/2 ton seems to be low a quart of coolant every 2-3 months. First alerted to this during a oil change, check it monthly and need to add alittle to the resevoir every other month. The temp guage never goes over half way. I do smell antifreeze after I shut the truck down after a significant drive, but only if I walk to the front of the vehicle.
Ok. So what’s the question? You have a leak in the cooling system. Someone has to find it and address it. If you want to quickest and most effective way find your best local radiator shop and have them pressure test the system.
The 4.3, 5.0, and 5.7 engines had the GM intake gasket leak problem in the late 90s/early 2000s. I’m not sure if this was fix by 2005. Any coolant in the oil, even a few drops is a sign of an intake gasket leak. The only sign of an intake gasket leak on my 2000 Blazer (4.3) was a slow loss of coolant (~1 pt/month) and an occasional smell of coolant at the front of the truck.
There was no milky goo at the oil filler cap (sure sign of excessive moisture in the oil) and the oil was clean. A few drops of coolant showed up when the last of the oil was drained out of the pan. That was enough for my mechanic to recommend getting the gasket repaired. The dealer confirmed my mechanic’s diagnosis and replaced the gasket. This is not a repair to hold out on, because any amount of coolant in the oil displaces the oil from the main bearings, wrecking the engine in a short time.
A few years ago the Blazer had the same symptoms and it turned out to be a crack at the top of one of the radiator’s side tanks. I didn’t find the crack until the radiator fan shroud was removed.
You have a small leak that needs to be found. Small leaks can only get larger over time.
I had this exact same problem with my Accord, I know it’s a different animal, but anyway: Coolant was leaking slowly at the radiator filling neck which required replacement of the radiator.
Take care of this while it’s a minor problem, rather than a major one.
I had this type of problem (coolant odor, but with negligible loss of coolant) in one of my older Subarus. It turned out that I only needed to “tweak” the clamp on a recently-replaced radiator hose. Hopefully yours will be as simple to fix as mine was.
On this vintage of GM truck with the 4.8,5.3,6.0 liter V8, the most common coolant leak is the water pump gasket. Of course if it’s the 4.3, I’d be looking at the intake gaskets.