Know how your engine oil works
A conventional car will stop running once it’s out of gasoline, but if it runs out of oil, there’s a good chance it might never run again. Oil is essential, and without it, an engine can be irreparably damaged within minutes. There are different types, different viscosities, and opinions on how often it should be changed, and it’s important to know in order to protect your investment.
Engines contain parts that move several thousands of times a minute, most of them only thousands of an inch away from their neighbours, and at very high temperatures. Oil lubricates these parts and helps to dissipate heat. It also suspends the carbon particles caused by gasoline combustion, and changing this dirty oil helps keep the engine clean.
Just like engines, oil is constantly being reengineered and improved. About 80 per cent of it is base oil, while the remaining 20 per cent is a blend of various antioxidants, detergents, and anti-wear agents.
Each bottle has a series of numbers on it, such as 5W-30, which indicates its viscosity — how well it flows at a specific temperature. Oil thickens when it’s cold, and become thinner and freer-flowing when it’s hot. Although many people think the W indicates “weight,” it actually stands for “winter.” Most motor oils are a blend of thinner and thicker oils, so they’ll flow easily and provide protection over a wide temperature range.
A lower first number indicates its cold-weather ability, while a higher second number means the oil’s better able to handle hot weather. For example, 5W-30 oil is formulated more for winter use, while 10W-40 oil is more for summer. (The numbers are engineering standards, not actual temperatures.)
And what’s up with “synthetic” oil? It sounds like something made entirely in a lab, but most are made from fossil-fuel petroleum. Unlike conventional oil, synthetic oil is treated with a synthetic process that gives the molecules a consistent size and shape. This improves flow and lubrication, which can increase the length of time between oil changes.
That’s where things get muddy: just how often should you change your oil? It needs to be regularly drained and replenished not just because it gets dirty, but because those additives eventually break down, reducing their ability to protect the engine.
The general rule used to be about every 5,000 kilometres, but between engine and oil improvements, many automakers are recommending every 10,000 km or more, and you should check your owner’s manual for the service intervals. Some vehicles have maintenance reminders in their information screens, which calculate not just time and distance, but driving habits as well to determine when oil should be changed. Always change the oil filter at the same time.
It’s usually recommended that you change the oil more frequently for “severe use,” but that’s not just the tough stuff like towing a trailer. It also means a lot of very short trips when the engine doesn’t get hot enough to remove any internal condensation. If this describes your usual routine, try to take a drive of at least 30 to 45 minutes once a week. If that isn’t possible, change your oil every three months, no matter what the mileage is.
In any case, you’ll never damage your engine by changing the oil too frequently. But you can do harm by driving with too little of it. All engines consume oil, some more than others and especially as they get older, and you should check the level periodically. To do this, turn off the engine and let the vehicle sit for a few minutes, so the oil drains to the bottom for measuring. Pull out the oil dipstick and wipe it clean. Insert it again, and then pull it out and check the markings on the stick.
If it’s low, add a little and then check it again. Don’t overfill it, which can be as bad as having too little, because the oil will foam and won’t properly protect the engine. Rather annoyingly, some high-end manufacturers don’t include a dipstick anymore, and instead provide an oil level reading in the vehicle’s information screen. It’s convenient, but electronic sending units sometimes malfunction.
The oil in your engine is pressurized, and a pump sends it from the reservoir at the bottom of the engine up to the top, where it lubricates moving parts. All vehicles have an oil warning light, which illuminates if the system loses pressure. If it comes on, pull over as soon as you can and shut the engine off to avoid damage.
The light indicates insufficient oil pressure, but it doesn’t measure how much oil is actually in the engine. The warning could be caused by an insufficient amount of oil, but it could also be that the oil pump has malfunctioned and oil isn’t circulating. Add oil if it’s low, but if the light stays on after you’ve filled it, or if the dipstick shows the engine has enough oil, it’s better to have it towed to a shop than to drive it and risk serious damage. Unlike drivers, engines are always best when they’re “well-lubed.”