You should add engine oil to your car under two main circumstances: as part of a routine oil change based on your vehicle's maintenance schedule, or as a necessary top-off when the oil level is low. The most reliable way to know when to add oil is to check the dipstick regularly, ideally once a month or before a long trip.
Routine Oil Changes: This is a preventative maintenance task. Most modern cars have an oil change interval of 5,000 to 10,000 miles, but this varies significantly. Always consult your owner's manual for the manufacturer's specific recommendation. Newer synthetic oils often allow for longer intervals. The car's oil life monitoring system, if equipped, will also alert you when a change is due.
Topping Off Oil: If you see the oil pressure warning light (which looks like an old-fashioned oil can) illuminate while driving, pull over and turn off the engine immediately. This indicates a serious lack of oil pressure, not just a low level. For a low-level warning, or if your monthly dipstick check reveals the oil level is below the "MIN" or "ADD" mark, you should add oil. It's crucial to use the type and viscosity grade specified in your manual.
| Common Oil Viscosity Grades & Typical Applications | |
|---|
| 0W-20 | Commonly used in newer Honda, Toyota, Ford, and GM models for maximum fuel efficiency. |
| 5W-30 | A very common grade for a wide range of gasoline engines. |
| 5W-20 | Frequently specified for many Ford, Chrysler, and Japanese models. |
| 10W-30 | Often used in older vehicles or in warmer climates. |
| 5W-40 | Common for European performance cars and some diesel engines. |
Never overfill the oil, as this can cause damage. Add oil gradually, in small increments (usually half a quart at a time), and recheck the dipstick until the level is between the "MIN" and "MAX" marks.
