30 weight oil? 50 weight oil? Making sense of oil weights

Ever wondered what the oil weight numbers on that bottle of Genuine Subaru Oil mean? Oil grades refer to the oil’s viscosity – defined as resistance to flow – and are represented by a numerical value followed by the letter “W” (which stands for “Winter”) and another number.

The number in front of the “W” represents the oil’s viscosity in cold temperatures — such as during engine start-up. A lower first number means that the oil will flow more easily in cold conditions, which is crucial for smooth engine startup and proper lubrication, especially during those chilly winter mornings. Engines with a 5W designation are typically recommended for use in Canada.

The second number represents the oil’s viscosity at higher temperatures, and thicker oils provide better protection under high heat and heavy load conditions.

The best oil weight for your vehicle is defined in the owners’ manual and it’s important to follow that recommendation. Using the right product protects your engine, increases power and optimizes fuel economy.

At the dealership, service professionals use Genuine Subaru Motor Oils formulated specially for the Subaru BOXER and are designed to withstand rigorous engine operation without viscosity breakdown and prolong engine life by protecting against varnish and deposits.

Subaru vehicles come from the factory with natural petroleum-based engine oil but synthetic oils, which offer consistent viscosity across a wider temperature range, are recommended. Conventional oils tend oxidize and acidify more easily. Subaru advises that once synthetic oil is used, users should keep using it and not switch back and forth with natural petroleum-based oil.

Subaru recommends drivers get in the habit of checking the oil every two times they fill up — or at least at a minimum of once every 2,000 km. Dealers will do an oil changes as part of each 10,000 km scheduled dealership service.