Temp gauge

The temp gauge has started reading high. I checked the radiator level. It had dropped. The rad took a pint to bring it back up the level. I checked the oil. That too was down a bit. I had to buy a can of 20/50 before I could top Degsy up. I put in a litre. I had a errand to run so went in Degsy. The temp gauge is back to normal.