Tech Tip: What Does SAE 10W-30 Actually Mean?

Tech Tip: What Does SAE 10W-30 Actually Mean?

We all know to check the owner's manual to find out which weight oil should be used in the engine of a vehicle, and also generally know to only use motor oils with American Petroleum Institute Certification, designated by the starburst displayed clearly on the container, in most vehicles. But what really is the difference between a SAE 10W-30 and a SAE 10W-40, or for that case, SAE 0W-20 motor oil?

We all know to check the owner’s manual to find out which weight oil should be used in the engine of a vehicle, and also generally know to only use motor oils with American Petroleum Institute Certification, designated by the starburst displayed clearly on the container, in most vehicles. But what really is the difference between a SAE 10W-30 and a SAE 10W-40, or for that case, SAE 0W-20 motor oil?

To better understand the numerical code used, a brief explanation is in order. When referencing motor oil weight, you are actually referring to the viscosity grade or the tendency of a liquid to flow slowly or quickly. The Society of Automotive Engineers (SAE) developed a grading system to designate the viscosity level of single grade and multigrade motor oils. In single grade oils, the lower the number, the better it flows at cold temperatures. Likewise, the higher the number, the thicker the oil. In regard to multigrade oils, the first number in the code, such as “10W” in SAE 10W-30, means that the oil can still be pumped by the engine at a temperature as low as a single grade 10W oil. A “5W,” like in SAE 5W-30, can be pumped at an even lower temperature, and a “0W,” like in SAE 0W-30, will pump at the lowest tested temperatures. The W in the designation is commonly thought to represent Weight, but in fact stands for Winter. The second number, “30”, indicates how well the oil will flow when heated to 100° C/212° F or higher.

As engines have become more technologically advanced, engine clearance levels and viscosity grade recommendations may have been reduced, hence the reason your father swore by SAE 20W-50 and your engine calls for SAE 5W-30. If a thicker oil is used in some of today’s high-tech, small clearance engines, oil pressure may increase, but the possibility of improper lubrication can result if the oil cannot adequately flow through the engine. Engine manufacturers carefully select the recommended motor oil viscosity grade for each specific engine, which is why the owner’s manual recommended viscosity should always be used.

Courtesy of Quaker State.

For additional information on products offered by Quaker State, visit www.Qpower.com.

You May Also Like

CITGO Enters EV Space with Pilot Program Launch

The CITGO location on 11 Mile Road in Michigan now offers both regular transportation fuel and EV charging stations.

CITGO Petroleum Corporation, along with marketer Folk Oil Company, recently launched an electric vehicle (EV) charging pilot program they said is designed to meet the needs of EV drivers in Battle Creek, Mich. The CITGO location at 15551 11 Mile Road now offers both regular transportation fuel and EV charging stations. For added consumer convenience, EV chargers include both Charging System (CCS) and the North American Charging Standard (NACS) plugs, the companies said.

TS Toolbox Guide February 2024

Here’s a look at some of the core feature and modern frills to consider when it’s time to move into a new office.

toolbox guide illustartion
Stellantis Increasing Production of Electric Drive Modules

The company will add EDM production in Szentgotthard, Hungary, targeted to begin in late 2026.

Embracing Cutting-Edge Solutions the Industry has to Offer

Embracing cutting-edge solutions is strategic and imperative for technicians navigating the constantly changing landscape of automotive maintenance and repair.

Nadine Battah
Tool Time Podcast: Clore Automotive

Jim O’Hara from Clore Automotive joins Nadine Battah and Eric Garbe.

Other Posts

TechShop, ShopOwner Offer $50 For Good Guesses

Guess the Tool for a chance at cold hard cash!

GM, Honda Begin Volume Production of Fuel Cell Systems

GM and Honda will produce fuel cells that will be two-thirds less expensive compared to Honda’s 2019 Clarity fuel cell.

Toyota Bringing Battery EV Production to Kentucky

It will invest $1.3 billion at its flagship Kentucky facility for future electrification efforts, including assembly of an all-new, three-row battery electric SUV for the U.S. market.

Repairify Announces Executive Leadership Changes

The company has named Craig Edmonds as president of asTech among other executive appointments.