This article is pretty weak, but its the only one I've seen recently in main stream media:
Making Sure the Oil Is Up to the Job
January 21, 2007
Motoring
By KEVIN CAMERON
ONCE a ritual of doting car owners, the weekend oil change has nearly disappeared from suburban driveways, as much a victim of extended change intervals — commonly 10,000 miles or more on new models — as the scheduling conflicts created by scout meetings and soccer practices.
The growth of 10-minute oil change franchises has also made it easy for owners to turn a messy chore over to an efficient operation. While these shops are a great convenience, they have also had another effect: fewer owners are shopping for their own oil and selecting the brand and grade recommended by the owners’ manual.
Using oil that meets the automaker’s requirements has become more important as engines get smaller and work harder. At the same time, higher prices and incentives to use less oil seem to conflict with the desire to change the oil more frequently than the automaker’s suggested interval.
What do motorists need to know about engine oils? Dennis L. Bachelder, a mechanical engineer who works on engine oil certification at the American Petroleum Institute, an industry group, said it was essential to know that easy-to-find information on the oil container related directly to the lubricant’s ability to protect engines from wear, corrosion and deposits. Some consumers still dismiss the matter, he said, thinking that “oil is oil” and then choosing the cheapest product.
The label on the back of a container of oil that has been certified to A.P.I. standards has two circles. The circle with black gear teeth around its perimeter is the A.P.I. certification mark, indicating that the oil meets certain standards.
Next to that symbol are the two concentric circles of the A.P.I. service symbol. In the center circle is the oil’s viscosity grade — a measure of its thickness and ability to flow at low temperatures. In an arc at the top of the outer circle are the words A.P.I. Service, followed by the letters of the A.P.I. service category.
The service category designates which methods of oil testing were used to certify the oil at a specific level of protection. Both the viscosity grade, as measured according to Society of Automotive Engineers procedures, and service category of oil required are found in the owner’s handbook.
Oils lubricate mainly by forming a fluid wedge between moving parts so they cannot touch or damage each other. You can see a lubricant wedge work when you slide a business card across a table. The card glides on a thin layer of air, which serves as a lubricant. Keeping the moving parts separated depends on both the viscosity of the lubricant and on the relative motion of the parts.
Higher viscosity numbers in general indicate an ability to form thicker oil films, but because friction and the amount of heat generated increase with oil viscosity, oil choice has to be a compromise. Modern engines have extremely smooth contact surfaces that let them use thinner, lower-viscosity oils than in the past.
To supplement the normal oil film, additives are included in the oil. An antiwear additive helps when surface-to-surface contact creates hot spots, forming a low-friction protective coating at those spots; if friction rubs this away, additives in the oil form the protective layer again.
Other oil additives called dispersants keep sludge and varnish-forming elements from adhering to parts where they could cause sticking. Instead, surrounded by dispersant molecules, they are swept to the oil filter, where they are trapped. Still others form corrosion-resistant layers that prevent moisture damage on metal surfaces.
These additives are consumed during engine protection and oil gradually becomes loaded with carbon or moisture. That is why frequent oil changes are important, even when using synthetic oils that offer better chemical stability and would otherwise permit the change interval to be extended.
Oil has improved as engines have become smaller and forced to work harder. The original SA Service Category ended in 1930, replaced by the more capable SB, and so on down to today’s extremely capable SM oils. Oil is not just oil.
http://www.nytimes.com/2007/01/21/automobiles/21OIL.html?ref=automobiles
Making Sure the Oil Is Up to the Job
January 21, 2007
Motoring
By KEVIN CAMERON
ONCE a ritual of doting car owners, the weekend oil change has nearly disappeared from suburban driveways, as much a victim of extended change intervals — commonly 10,000 miles or more on new models — as the scheduling conflicts created by scout meetings and soccer practices.
The growth of 10-minute oil change franchises has also made it easy for owners to turn a messy chore over to an efficient operation. While these shops are a great convenience, they have also had another effect: fewer owners are shopping for their own oil and selecting the brand and grade recommended by the owners’ manual.
Using oil that meets the automaker’s requirements has become more important as engines get smaller and work harder. At the same time, higher prices and incentives to use less oil seem to conflict with the desire to change the oil more frequently than the automaker’s suggested interval.
What do motorists need to know about engine oils? Dennis L. Bachelder, a mechanical engineer who works on engine oil certification at the American Petroleum Institute, an industry group, said it was essential to know that easy-to-find information on the oil container related directly to the lubricant’s ability to protect engines from wear, corrosion and deposits. Some consumers still dismiss the matter, he said, thinking that “oil is oil” and then choosing the cheapest product.
The label on the back of a container of oil that has been certified to A.P.I. standards has two circles. The circle with black gear teeth around its perimeter is the A.P.I. certification mark, indicating that the oil meets certain standards.
Next to that symbol are the two concentric circles of the A.P.I. service symbol. In the center circle is the oil’s viscosity grade — a measure of its thickness and ability to flow at low temperatures. In an arc at the top of the outer circle are the words A.P.I. Service, followed by the letters of the A.P.I. service category.
The service category designates which methods of oil testing were used to certify the oil at a specific level of protection. Both the viscosity grade, as measured according to Society of Automotive Engineers procedures, and service category of oil required are found in the owner’s handbook.
Oils lubricate mainly by forming a fluid wedge between moving parts so they cannot touch or damage each other. You can see a lubricant wedge work when you slide a business card across a table. The card glides on a thin layer of air, which serves as a lubricant. Keeping the moving parts separated depends on both the viscosity of the lubricant and on the relative motion of the parts.
Higher viscosity numbers in general indicate an ability to form thicker oil films, but because friction and the amount of heat generated increase with oil viscosity, oil choice has to be a compromise. Modern engines have extremely smooth contact surfaces that let them use thinner, lower-viscosity oils than in the past.
To supplement the normal oil film, additives are included in the oil. An antiwear additive helps when surface-to-surface contact creates hot spots, forming a low-friction protective coating at those spots; if friction rubs this away, additives in the oil form the protective layer again.
Other oil additives called dispersants keep sludge and varnish-forming elements from adhering to parts where they could cause sticking. Instead, surrounded by dispersant molecules, they are swept to the oil filter, where they are trapped. Still others form corrosion-resistant layers that prevent moisture damage on metal surfaces.
These additives are consumed during engine protection and oil gradually becomes loaded with carbon or moisture. That is why frequent oil changes are important, even when using synthetic oils that offer better chemical stability and would otherwise permit the change interval to be extended.
Oil has improved as engines have become smaller and forced to work harder. The original SA Service Category ended in 1930, replaced by the more capable SB, and so on down to today’s extremely capable SM oils. Oil is not just oil.
http://www.nytimes.com/2007/01/21/automobiles/21OIL.html?ref=automobiles
