[Engimaneer]

Possible leak is the best place to start.

Check the area that you usually park in for a dry white stain or for a dark permenant water type mark.

Some leaks cannot be seen dripping, but a give away can be when you get crystalised coolant on pipework/under the car.

Bump

 

[Engimaneer]

i had the same problem the other day, drove from west---east london and the temp kept dropping back to 0 but then kept coming back to 90 so when i got home later that eveing i looked at the coolent and there was hardly any left?? so ive topped it up, i cant seem to see any leakes or anything..just going to judge it over the next couple of days and see what happends.

the mk4 likes to drink oil and ive topped that up too. atm im just putting it down to the weather but lets see what happends...

Both of those are very bad symptoms and important issues.

You should get it checked out.

Ideally, NO oil should ever be lost, and coolant generally should never need topping.