Thankyou. I will buy a new cap tommorow, i got one ordered and it will be in stock then.

After i have driven the car should the water be higher or lower in the expansion tank and again after the car has been sitting a day or two should it be higher or lower in the expansion tank?

I still dont know why i have to top up... the level never seems the same from day to day, it can be on the minimum, then it can be half to max next week, then below the minimum... so i add some...

I dont know if i am doing the right thing or if i should be worried...

What i do know is that after i add some water to bring it to say half way between min and max and then use the car for a month and then re-check the level it usually always is below where i topped it too so i add more...

This last month it was below the min for the first time ever... so i added quite alot and had it checked (unsuccesfully) for leaks.