what does it mean when the oil level has dropped to a negative number?

Question

I usually bring my car in for an oil change when the oil level indicator gets down to about 5%. However, my oil light on the dashboard has been on for a few weeks, and I was aware that it was getting low but I was really busy and didn't get around to bringing it in. When I went out to my car yesterday morning The oil level indicator said it was -2. I went and bought a quart of oil and put that in, but then the oil level said -5 so I bought 3 more quarts and poured those in and put it in, but now it is at -20. What does that mean? Shouldn't it have reset or something when I added the oil?

Answer 1

Uh oh, looks like you've been buying anti-oil, the kind that registers as negative oil! You better get some normal oil to replace all that negative oil!

Just kidding. Do not actually do that, you don't want to overfill your oil.

The "oil level indicator" you're talking about is most likely actually the oil life indicator, which is commonly referred to as part of Honda's Maintenance Minder system. In other words, it doesn't actually indicate the amount of oil in your engine, it actually provides an estimate on your oil life as a reminder for when you need to bring your car in for service. After the oil is refilled, the maintenance minder will need to be manually reset. You can read all about it on a Honda FAQ here.

From the FAQ you can see that when you run past 0% on the oil life indicator:

The display will start to show negative mileage. This indicates how many miles that the vehicle is past due for service.

Since you haven't reset the maintenance minder, it will continue to show a negative value until it is reset either by yourself, or by a mechanic who has serviced your car.

If you're not familiar with the process for draining and replacing the oil in your engine, then it is recommended that you keep an eye on the oil level from your dipstick, and bring your car in for service when you have the opportunity. Otherwise, you should replace your oil, and then follow these steps (from another Honda page) to reset the indicator:

1. Turn the ignition to run (one click before starting the engine).
2. Press the Select/Reset button located on either your steering wheel or as a knob on your dash. Depending on your model, either scroll through or press the knob repeatedly until "Engine Oil Life" or "Engine Oil Indicator %" is displayed.
3. Press and hold the Select/Reset button for 10 seconds. The Engine Oil Indicator will begin to blink.
4. If your display reads "Engine Oil Life", select the Reset mode by pressing the Info button on the steering wheel. Then press and hold the Select/Reset button for more than 5 seconds to return your oil life to 100%.

Those instructions are for general Honda models, so it may vary slightly for your car.