And the debate continues - a few things a quick google search turns up
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Q: Who benefits from the 3,000 mile oil change?
A: The Oil industry, not the consumer.
A look at many recent model owners manuals reveals a recommended 5000 to 7500 mile oil drain interval, while European vehicle manufacturers recommend even longer drain intervals.
The implications of the extended drain interval on the automotive aftermarket are mixed. There are two clear losers – the quick lube industry and the oil filter industry. According to a past National Oil and Lube News, Marc Graham, then president of Jiffy Lube International, said that for every 100-mile reduction in fast lube customers’ oil change intervals, the industry could realize $105 million in sales. Clearly, the converse is true, so a widespread extension of drain intervals would have an immediate and negative impact on the industry. This could be partly offset by the need for synthetic oils which traditionally command a premium that might help compensate for the lost volume.
Almost all 2005 and later General Motors vehicles are equipped with its Oil Life System, which makes use of a color-coded system to alert the driver when it’s time to change the oil. A “yellow” condition indicates that it’s time to think about changing the oil, while a “red” condition indicates that the oil is past its service life. According to GM, the typical drain interval for vehicles equipped with the Oil Life System is 8,500 miles, which will result in a savings of 6.6 million gallons of oil and $145 million for 2005 model-year drivers over the lives of their vehicles.
General Motors is actively seeking to extend oil drain intervals even further. In fact, the company recently asserted that 20,000 mile oil drain intervals are possible with existing engine technology and synthetic oils meeting current specifications, while 30,000 mile oil change intervals are achievable with appropriate motor oil quality and minor engine modifications.
“Drain intervals are a very specific goal for GM, and are being managed in a logical and planned fashion,” says James A Spearot, director of GM’s Chemical & Environmental Sciences Laboratory in Warren, Mich. “Longer drain intervals are desirable to meet customer demands for reduced maintenance and convenience, and for the environmental benefits that come with less oil handling. And, in the end, longer drain intervals will help us with our warranty protection goals.”
Today, with vehicle manufacturers recommending longer and longer drain intervals and the increasing use of oil monitoring systems, the practice of extending drain intervals has become more mainstream and forced more motor oil companies to take notice. ExxonMobil, for example, recently introduced a line of long drain motor oils, and other motor oil companies will likely follow. As more motor oil companies begin offering extended drain motor oils, the extended drain interval idea pioneered by AMSOIL in 1972 will become increasingly common.
According to a special report released last May by the Motor & Equipment Manufacturers Association (MEMA), synthetic motor oils are key to extended drain technology: “Extended drain technology is primarily based on the availability of synthetic oils. While the additives in conventional, non-synthetic oils allow them to function longer than the tradition 3,000 miles, it is primarily the synthetic base stocks that allow the oil to last much longer. Synthetic oil offers many advantages in durability versus conventional petroleum oil and it is all based on the synthetic oil’s superior heat and oxidation resistance. Synthetic oil is more accurately controlled at the molecular level and therefore can be engineered to resist the forces in an engine that work against oil durability.”
Dark oil does not indicate the need for an oil change. The way modern detergent motor oil works is that minute particles of soot are suspended in the oil. These minute particles pose no danger to your engine, but they cause the oil to darken. A non-detergent oil would stay clearer than a detergent oil because all the soot would be left on the internal engine parts and would create sludge. If you never changed your oil, eventually the oil would no longer be able to suspend any more particles in the oil and sludge would form. Fortunately, by following the manufacturer's recommended oil change interval, you are changing your oil long before the oil has become saturated. Remember, a good oil should get dirty as it does it's work cleaning out the engine. The dispersant should stop all the gunk from depositing in the oil pan.
The only real way to determine whether oil is truly in need of changing is to have an oil analysis performed. Since most people don't want to bother with this, it's acceptable to err heavily on the safe side and simply follow the manufacturer's recommended change interval for severe service. There are still a few cars that specify 3K intervals for severe service, but not many. If you look at countries other than the U.S., the oil recommended change interval is much higher than even the normal interval specified by vehicle manufacturers in the U.S.
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"Assuming that the current oil change interval for DIFMers is approximately 5,200 miles, every 100-mile reduction in fast lube customers' oil change intervals delivers $105 million in sales for the industry," said Marc Graham, president, Jiffy Lube International, and chairman of AAIA. "If consumers had their oil changed at 4,200 miles, the aftermarket would realize an additional $1.1 billion."
http://www.doityourself.com/stry/extendeddrain
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