When you heat your home with home heating oil, it is important to keep an eye on the tank level just like you watch the fuel gauge in your car. Some oil tanks have external floating gauges that you can simply look at to determine how much fuel you have left. However, most oil tanks do not have these gauges and you must check them manually. Manually checking the heating oil level in an oil tank requires the use of a straight stick. A number of oil companies offer these "dipsticks" at no charge.
Turn the top fill valve cap counter-clockwise and remove the cap from the tank. The fill valve is the larger of the two caps on top of the oil tank. This is where the delivery driver fills your oil tank.
Insert a dry 6-foot-long straight stick into the fill hole until the end of the stick rests in the bottom of the tank. Insert the stick slowly and straight. Mark the stick with a pencil where the stick meets the top of the fill hole when fully inserted.
Pull the stick out of the tank and place it against the end of the tank, if you have a standing tank. Look at the wet mark to determine how full or empty your tank is. If you have a tank that is half submerged in the ground, look at the distance between the wet mark and the pencil mark to determine your oil level.
Thread the cap back onto the fill valve hole until you can no longer turn it by hand.