Car Engine Oil / Lubricant Rating System
by: Kevin Schappell
I receive a lot of questions regarding oil and the least understood part is the number system used to rate oils.
Oil weight, or viscosity, refers to how thick or thin the oil is. The temperature requirements set for oil, by the Society of Automotive Engineers (SAE) is 0 degrees F (low) and 210 degrees F (high).
Oils meeting the SAE's low temperature requirements have a "W" after the viscosity rating (example: 10W), and oils that meet the high ratings have no letter (example SAE 30). Oil is rated for viscosity by heating it to a specified temperature, and then allowing it to flow out of a specifically sized hole. Its viscosity rating is determined by the length of time it takes to flow out of the hole. If it flows quickly, it gets a low rating. If it flows slowly, it gets a high rating.
The Oil 'W' Rating
Engines need oil that is thin enough for cold starts, and thick enough when the engine is hot. Since oil gets thinner when heated, and thicker when cooled, most of us use what are called multi-grade, or multi-viscosity oils. These oils meet SAE specifications for the low temperature requirements of a light oil and the high temperature requirements of a heavy oil. You will hear them referred to as multi-viscosity, all-season and all-weather oils. An example is a 10W-30, which is commonly found in stores. When choosing oil, always follow the manufacturer's recommendation.
Wondering how you can save money and protect your vehicle at the same time? Consider switching to synthetic oil and changing your oil at greater intervals.
by: Kevin Schappell
Kevin Schappell maintains http://www.carbuyersclub.com where he gives advice on car maintenance, buying, selling,
insurance, and financing. A mechanical engineer and car guy, Kevin has decided to spend his online time helping others learn about carmobiles.
If you found this page useful please click the +1 button below to tell Google that its a great page!
Please share this page with others, and leave a comment, we value all feedback!
Was this page useful? Do you have something to add? Do you disagree?
If your comments meet our guidelines then we will publish them (you do not need to register!)
Ttradesman - click here to join our network to receive leads from customers in your area