Most auto manufacturers require you check the oil after the car has been warmed by starting it in place for 3-5 minutes. Check your owner’s manual if there is any doubt. [3] X Research source To be safe, you should check your oil every month, and more frequently if you have to drive long distances.

If the line is close and you are unsure whether or not to add oil, drive the car and check the oil again after 2-3 weeks.

If the oil looks milky or white you could have a coolant leak and must get the car towed to a mechanic immediately. If the oil has metallic particles or bits in it, get it to a mechanic immediately. [7] X Trustworthy Source Consumer Reports Nonprofit organization dedicated to consumer advocacy and product testing Go to source If the oil seems dirty or sludge-like, it’s time to change your oil. [8] X Research source You should not be filling up the oil every few weeks or month – this could be the sign of a leak. [9] X Research source

The first number should be at least 5W or lower if you live in very cold areas (see your owner’s manual), as oil can get too thick for the car to start if the winter viscosity is too high. Your owner’s manual will have a recommended viscosity rating for your car. If there is only one number, as found in some older cars, your car uses a “single-weight” oil. [11] X Research source

Some certifications change as the get more modern. The current API designation is SL, though it has been SJ and SI before. Again, refer to your manual for your car.

Blending oils, however, is perfectly acceptable, so you do not have to shell out for pure synthetic oil if it seems too expensive. [12] X Research source

Consider switching in a higher weight oil (40 for 30) for the summer months, when it gets hotter, instead of switching to a multi-weight oil like 20W-40W. [13] X Research source

Always check your owner’s manual to see how often you need to get your oil changed – it may be as soon as 3,000 miles or as infrequently as every 20,000 miles. Most experts recommend changing oil every 5,000 miles. [14] X Research source

A funnel will make it easier to add oil without spilling it on the engine.