To keep your oil clean and your engine healthy, it's important to follow your vehicle manufacturer's maintenance recommendations.
Also check your oil level with the dipstick, if applicable, every time you fill up with gas. Check your oil for:
- bubbles or foam
- a milky appearance
- a strong smell of gasoline
These signs could mean you have water or fuel contamination or your oil level could be too high.
If you change your oil yourself, be sure to dispose of the used motor oil in an environmentally responsible manner.
What Does Oil Do Anyway?
Oil keeps everything lubricated, cool and clean - which is why it gets dirty.
When you start your vehicle, oil begins lubricating your engine. Numerous additives within the oil help it cool and reduce friction between internal moving parts. Oil also cleans away dirt and contaminants, preventing premature engine wear.
For example, for every gallon of gasoline that is consumed, about one gallon of water is generated. Most of this water turns to steam and exits through the tailpipe (which you may notice on cold mornings when that water actually drips from the tailpipe). Some of this moisture does get into the dead air space of your engine. There, it mixes with other chemicals and forms sulfuric and nitric acid. Dirt and residual fuel will also find their way into this dead air space. The motor oil must continually keep this area clean so it sweeps away the dirt and absorbs the acids and fuel.
As a result of all the dirt and contaminants it picks up, motor oil needs to be changed regularly. Also, when motor oil becomes old and dirty, you're no longer getting the full benefit of the additives it contains. The motor oil becomes less effective at cooling and lubricating your engine. What's worse, the increased friction and chemical buildup in used motor oil can deteriorate your engine's moving parts.
Motor Oil: Synthetic vs. Regular
Synthetic motor oils are designed to excel at extreme temperatures. Regular motor oils are mineral-based: they come from crude oil that is taken out of the ground and run through a refinery. Synthetics, on the other hand, are man-made in a chemical plant. They tend to be more consistent in viscosity over various temperatures.
While synthetics can improve your engine performance, they don't' eliminate the need for regular oil changes. Synthetics can handle heat better than regular motor oil, but additives can only work for so long and the engine will still contaminate the oil.
You see those cryptic combinations of letters and numbers on motor oil bottles everywhere. What do they mean?
To decipher them, you have to understand viscosity. Viscosity measures how much the motor oil can resist flow. In other words, if you tip a motor oil bottle over, how fast it spills out indicates its viscosity. The more viscous, the slower it moves.
To indicate viscosity, the SAE (Society of Automotive Engineers) developed a standard scale.
0W is thinnest ("W" stands for winter)
60 is thickest
The recommended multi-viscosity oil you use in your vehicle is usually good all year round because it can respond to a range of temperatures. That's why you see two numbers on most oils.
For example: 10W30
This means the viscosity is at 10W when the engine is cold and 30 when the engine is hot. Low viscosities are good for cold temperatures (hence the "W" association) because the oil is thinner. Thinner motor oil flows more easily and moves quickly. When you start a cold engine up again, motor oil needs to travel to the top of the engine, where it trickles back down. Since motor oil is vital to lubricating your engine, it needs to move quickly and low viscosity helps it do just that.
When your engine heats up, higher viscosities mean the motor oil won't thin out too much and will keep parts separated by a film of oil. So your motor oil is always maintaining a delicate balance: it needs to flow well when the engine is cold but also retain enough body at higher temperatures to keep metal parts lubricated and separated. To find out what motor oil grade is right for your vehicle, check your vehicle's owner's manual.