Who Should Be Using A Different Motor Oil In Winter?

Some myths surrounding motor oil just won't go away, but there is truth to the notion that oils with higher viscosity ratings are better suited for warmer climates than lower viscosity oils. Since putting the wrong oil in your engine can cause problems, it's best to follow the recommendations found in your vehicle owner's manual to select the proper engine oil.

Basic small engines, like those found in some lawn mowers and generators, can call for the use of single-grade motor oils, while automobile engines use multi-weight oils. Single-grade oils, like SAE 30, don't have the same properties as multi-weight motor oils. Multi-weight oils are indicated by two different numbers separated by the letter W, like 5W-30. The first number is the oil's winter weight, derived by measuring the oil's dynamic or absolute viscosity. The second number is the kinematic viscosity of the oil at 100 degrees Celsius (212 degrees Fahrenheit), which simulates normal engine operating temperatures. Lower viscosity numbers indicate faster flowing oils.

While most people won't need to change oil types with the seasons, if you've moved your car from an area with warm winter temperatures to a place experiencing frigid, arctic weather, you may want to consider swapping to an oil with a lower dynamic viscosity. However, you should consult your owner's manual and a local mechanic first. Plus, anyone thinking about using their lawnmower to blow snow off their driveway in double-digit negative temps may want to use a different oil to avoid damaging the engine. Operating a car, motorcycle, or any four-stroke engine during winters in extremely cold climates could require the use of a different motor oil, but you should always check your owner's manual and consult an expert before making radical changes.

The Society of Automobile Engineers, or SAE, developed the standards for motor oil grades. While the SAE is now known as SAE International, the organization still works closely with automotive engineers and provides guidance on motor oil standards, among other things.

Using an engine oil that's too thick presents significant downsides, including potential engine damage. Using motor oil with a thicker viscosity than indicated in your owner's manual can make your car harder to start, cause unusual engine noises, and provide inadequate lubrication until the engine warms up, especially when it's cold outside. Hard starting can result from the crankshaft struggling to spin through a crankcase filled with thick motor oil. The extra engine noise can be a symptom of the lack of lubrication that occurs when the cold, thick motor oil can't squeeze through the tight passageways of the engine.

The single-grade SAE 30 motor oil offers sufficient engine protection across temperatures ranging from -5 degrees Celsius up to 35 degrees Celsius (23 to 95 degrees Fahrenheit). Engine operation in sub-freezing temps, down to -25 degrees Celsius (-13 degrees Fahrenheit), requires SAE 10W motor oil or a suitable multi-grade oil if allowed by the engine manufacturer.

The multi-grade SAE 10W-30 motor oil offers a range of -25 to 35 degrees Celsius (-13 to 95 degrees Fahrenheit), which closely matches the combined ranges of SAE 10W and SAE 30. The motor oils with the coldest temperature ratings are multi-grade oils that start with 0W, such as SAE 0W-30. According to the SAE chart, 0W-30 synthetic engine oil is suitable for use with ambient temperatures down to 35 degrees below 0 Celsius (-31 degrees Fahrenheit).