Head Gasket leak most likely.
Usually a blown head gasket.
Engine? 3.1L V6 are notorious for intake manifold gasket leaks. get it fixed soon or your engine is at risk. My Lumina had oil in coolant and coolant in oil. If there is tan foamy stuff on oil fill cap, coolant is in oil too.
Low oil causing the coolant to heat up to the point in which it's doing more harm than good so it's pushed into the overflow
Coolant is old.
Oil or trans fluid is getting in the coolant system. Have it checked out now. You can ruin lots of things by driving it.
A coolant overflow tank and a radiator overflow bottle serve similar purposes but are distinct components. The coolant overflow tank is designed to collect excess coolant that expands from the radiator when the engine heats up, preventing pressure buildup. In contrast, the radiator overflow bottle typically refers to a specific type of tank that captures overflow from the radiator directly, allowing for the coolant to return to the system as it cools. Both components help maintain the proper coolant level, but they may be used in different cooling system designs.
The overflow bottle may overflow if: 1. The car is overheating - this means after the coolant in the radiator gets heated up and expands it flows to the reserve bottle but the radiator doesn't cool down to suck back the coolant from the overflow bottle, but just keeps on sending coolant to the bottle. 2. You may have put excess coolant in the bottle - hence heated coolant from the radiator didn't get enough space.
The engine coolant reservoir or the overflow bottle.
maybe not. check engine oil for color and quantity. if oil is white to grey, then there is coolant leaking into engine.no pressure might be caused by bad radiator cap.this will also allow coolant to escape
yes
no antifreese
The radiator cap could be the cause of coolant reservoir overflow or backup. Have the cap checked to see if it is bad.