I am wondering why my car keeps drinking coolant. One minute it'll have low coolant then few hours later it's back. It's weird to explain.

There doesn't seem to be any leaks and I know the head gasket isn't going.

It's a APG engine (If correct) 1.8 Non turbo Seat Leon.

Tonight I have topped up oil as it was under min. Topped up coolant to max we will see in about 3 days if it dissapears again. If so can anybody give me an idea what it could be and a link to some sealants you can use to fix a hole if there is one. Light flashes but it seems to happen more on wet days. When weather is sunny it doesn't happen as often unless the coolant is generally low.

Sorry if not right forum new to the site