As dremd stated, you should go to Bobistheoilguy.com (link provided above) as the site is devoted to oils and other lubricants ... with a forum that has around 25,000 members. Mostly North Americans, but there are contributors from all over the world.
One subsection is devoted to UOAs ... Used Oil Analysis ... and you can see the PPM counts of wear metals, additives, etc ... from thousands of samples using different brands/types of oils.
Some general consensus items:
For modest drains (less than 4,000 miles or 6,500KM), it doesn't really matter what oil you use in a daily driver. Possible exceptions to this rule are sub-freezing conditions (synthetics flow much better in the cold than mineral oils) and severe, high-heat applications where synthetics of the same weight resist boil off better.
Extended drains are a more controversial subject … especially for 10,000+ miles (16,000+ KMs). They can be done safely in a vehicle that is operated in warm weather and where the operator tends to drive long distances. Synthetics help (they are more uniform and resist oxidation) but are not magic. Consider them for extending your oil change interval by 20% - 50% … NOT doubling or tripling it.
Not only does engine oil break down from heat and shear stress (it loses viscosity and becomes thinner), but it also becomes contaminated with wear metals, dust/dirt in the air and the byproducts of combustion. After a few thousand miles of short trips in cold weather, your oil can be 1-3+% fuel … which is a powerful solvent and a poor lubricant.
Engine air filters don’t trap all particles coming into the motor. From the combustion chambers, they migrate past the rings and into the oil. And once there, spin-on (‘full-flow’) oil filter cannot capture all particles in the oil. The smallest ones get through … unless you have a specialized ‘bypass’ filter arrangement that will capture particles down to a few microns.
Some engines are babied and still run into problems or early failure … while others are neglected or outright abused and seem to soldier on forever. However, these kinds of anecdotal stories are no reason to abuse/or neglect your engine. Regular maintenance is cheap insurance … and a poor-running engine is often an inefficient engine that uses more fuel than is otherwise necessary.
Bottom line: Change your oil … 2-3 times per year is ideal for most of us.
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--- Bror Jace
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