Ever notice some funky readings from your Smart Oil Gauge right after a fill? This can happen when the oil in the tank is simply too close to the sensor on the Smart Oil Gauge for it to pinpoint a precise reading. Once the level drops down a bit in the tank, everything goes back to normal and all is well. In case you're wondering, here's what's going on...

In a nut shell, the Smart Oil Gauge uses an ultrasonic sensor to determine how full the oil tank is. The operating range on this sensor is approximately 8” to 72”. This means that when the oil is less than 8” from the sensor, it is too close for the sensor to provide a precise reading. In many cases, when a tank gets topped off, the oil level is 5-6” from the top of the tank. This final level leaves an air space at the top of the tank for expansion of the oil as it warms up, and to prevent the driver from over-filling the tank if the pump isn’t shut off quickly enough.

Because the sensor cannot precisely measure the level in the top 8” of the tank (the sound wave simply bounces back before the sensor can react to it), the sensor will often read ‘Full (>XXX gallons)’ when the tank is full. The 8” mark is a different level depending on which style tank you have. Here’s the max level for the five most common tanks:

Level Jumping Around Right after a Fill

Occasionally, right after the tank has been topped off, the level may even bounce around a little bit, showing a decrease in the level, followed by a jump back to full. This typically only lasts a few days (depending on how quickly you’re using the oil), and then the level jumps back up to ‘Full (>XXX gallons)’.

You may be wondering what happens to the usage statistics when this happens. Fortunately, our software works behind the scenes to account for these funky readings right after the fill, so the usage statistics after a week or two tend to be quite accurate.

To illustrate what can happen right after a tank gets topped off, look at the figure below. This is a tank that was topped off immediately before the Smart Oil Gauge was installed. As you can see, the oil was so close to the sensor for a few days after the fill, that the readings actually went down for a bit before jumping back up to Full. After a few more days, the level dropped below the 8” mark (235 gallons on this particular tank), and the sensor was able to give nice precise readings again.

How can I prevent this from happening with my tank?

The nice thing about the Smart Oil Gauge is you can see exactly how much oil is in your tank at any given time. When your tank gets down to ¼ full, you can order a specific number of gallons to keep the tank under the maximum reading amount. For example, if you have a 275 gallon vertical tank, the maximum reading the Smart Oil Gauge can give is 235 gallons. So, if you wait until your tank is at 70 gallons, and order 150 gallons, the level should be approximately 220 gallons after the fill, and you will have a precise before and after depiction of what is in the tank.