Motor oil flows throughout a vehicle’s engine to keep it lubricated, cushioned and cleaned. How easily that oil flows depends on its viscosity, or weight. Motor oils with lower viscosity are thinner and flow faster than motor oils with higher viscosity, which are thicker.
When mechanics say it’s time to “winterize” your car, they usually mean changing out your motor oil for oil with lower viscosity.
How Cold Weather Affects Motor Oil
Colder temperatures thicken up and slow down motor oil. If the oil can’t move easily through the engine, it puts a strain on your car battery (which is already working harder in the winter) and your starter. (Here are 20 more things you must do to get your car ready for winter.)
Different Types of Motor Oils
When it comes to oil viscosity, there are straight-weight oils and multi-weight oils. Straight-weight oils are also called single-grade oils. They have one weight (or grade) and are labeled SAE##. The “SAE” stands for Society of Automotive Engineers, the association that created the weight scale for motor oil, and the number is the weight. The oil stays that weight year-round.
Multi-weight oils are one weight when it’s cold outside and a different weight when it’s hot outside. They’re labeled #W-##. The first number refers to the oil’s cold temperature weight, and the “W” stands for “winter.” The second number is the hot temperature weight. Multi-weight oil is actually the first weight and has additives that make it perform like the second weight when it’s hot.
What’s the Best Motor Oil During the Winter?
Always refer to your car’s user manual for the recommended type of oil for your car. Generally, 5W-30 is widely recommended because it’s actually good to use year-round. If you’re using a higher viscosity oil than that, your user manual may recommend changing to a lower viscosity for the winter. Just be sure not to go lower than the recommended viscosity because if the oil is too thin, it won’t provide enough lubrication for the engine.
Should You Use Synthetic Motor Oil?
It depends. Older cars are thought to be better off with conventional oil. Synthetic oils are petroleum-based like conventional oils, but they have been refined even further and have more artificial compounds and performance additives. Synthetic oil is typically recommend for newer cars, but it is more expensive than conventional oil. (Here’s what to look for when checking oil.)
How to Check and Change Motor Oil
When your engine is cold (it’s been off for at least three hours), remove the dipstick, wipe it clean and then reinsert. Pull it out slowly and smoothly and see if the oil level is within the indicator markers. If it is, it’s time to add more oil. To change your oil, you’ll need to jack up your car to drain the oil pan and pop the hood to change the oil filter.
Next, find out the ideal tire pressure in cold weather.