Date: Thu Jun 19 11:30:17 2008 Back to Contents

Author: Jerry DiMarco

Subject: Re: myth of oil change every 3,000 miles


Sounds like a potential science fair project. I started changing oil
every 3000 miles when I read a Consumer Reports survey about habits of car
owners whose cars lasted the longest or something like that. Guess it's
time to reconsider, and just in time since I'm getting tired of doing it
twice a year...


At 6/17/2008 09:29 AM, you wrote:
>Read this in the yahoo news, concerning the myth of changing the oil in a
>vehicle every 3,000 miles.
>Idea for new experiment in the physics labs or something already being done?
>Because of the many external conditions and parameters that have to be
>taken into account, calculating the precise maximum service interval using
>mathematical models alone is difficult. Now, Daimler AG has developed a
>more direct and precise way to monitor oil quality directly on board a
>Daimler uses a special sensor integrated into the oil circuit to monitor
>engine oil directly. Oil doesn't wear out, but rather dirt and impurities
>cause oil to lose its ability to lubricate properly, dictating the need
>for a change. Daimler uses the oil's "permittivity," that is, the ability
>to polarize in response to the electric field. If the engine oil is
>contaminated by water or soot particles, it polarizes to a greater extent
>and its permittivity increases.
>To evaluate the quality of the oil, permittivity is measured by applying
>an AC potential between the interior and exterior pipes of an oil-filled
>sensor to determine how well the oil transmits the applied electric field.

From Thu Jun 19 11:30:17 2008