Condensation occurs naturally inside your oil tank and can be caused by both hot weather and a change in weather conditions. Condensation, when built up over time, can drip into the fuel, causing contamination.

It can be difficult to check for contamination using a visual assessment. Instead it is recommend that after periods of extreme hot weather, and during the change from Summer to Winter, you should test that your heating system is operating as it should. That way if it is not, you have the time needed to get it fixed before the Winter weather catches you off guard.