I found this interesting article on the Autopia web site concerning changing engine oil:
Precious metals push spark plugs past the 100,000-mile mark. Tire manufacturers offer lifetime warranties on their radials. Even some transmissions are advertised as filled for life when they come off the assembly line.
The world is becoming a maintenance free place to drive. Well, almost.
Increasingly, motorists are asking the question, "How long can I go between oil changes?" In the same breath, they mention extended drain intervals and if it’s all right to go 7,500 miles or more between oil changes.
Motor oil is getting better all the time, but we’re not to the point where we can safely say that you should go beyond 3,000-mile or three-month oil change intervals if you drive in severe conditions.
Let me dispel a few myths about motor oil and when to change it.
Myth 1: I don’t drive in severe conditions, therefore I don’t have to change my oil as often.
You better be sure. There are a wide variety of severe conditions, such as stop and go driving hauling a load, short trips, extreme hot or cold temperatures and dusty areas.
Each of these conditions places a different stress on the engine, such as increasing operating temperatures and/or increasing the amount of contaminants the oil has to hold in suspension. These conditions really push the oil to the limit.
"Normal" driving conditions consist of taking long highway trips with few stops and starts. People in sales who spend a lot of time on the road or highway commuters may qualify. But, if you have any doubts, don’t wait to change your oil. Changing oil is a lot easier than changing an engine, and more economical.
Myth 2: Synthetics extend drain intervals.
Synthetics are superior. The superior protection is from the processing required to manufacture the base stocks and the different additive packages they require.
Despite better performance, synthetics need to be changed at regular intervals. The additives wear out, just like in conventional motor oils, and need to be changed.
Myth 3: As long as I change the oil filter, I can run longer between oil changes.
Changing the filter is great, but you’ve got to change the oil along with it, given that the oil'’ additives wear out and contaminants get into the oil itself. The filter can only capture the bigger particles suspended in the oil, not replenish spent additives.
Myth 4: Over the road trucks sometimes have oil change intervals as high as 15,000 miles. If they can do it, can I?
No. There are a number of fundamental differences in the lubricating systems on larger trucks, compared with cars.
First, truck engines can use up to three gallons of motor oil; a car, four and a half quarts. Second, trucks spend most of their time on the country’s highways and away from stoplights; cars start and stop, stop and go a lot more.
Extending the oil change interval beyond what the manufacturer recommends can seriously shorten the useful life of your engine.
Don’t push the limits of the motor oil and flirt with damaging your engine, especially when chump change is all it takes for an oil change.
Dr. Fran Lockwood is the Vice President of Technology and Product Development for the Valvoline Company.
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Myth #2 is interesting. Although BMW policy has generally changed, suggesting oil changes AT LEAST once a year even if the OB - service indicator doesn't warrant it, IS that really often enough, especially if one usually drives short trips, city stop and go, etc.?
The longevity of synthetic oil has been brushed upon in previous oil related posts, and some of you do change it more regularly than the OBC indicates at your own expense, but how often is really too often, beyond the law of deminishing return concerning engine life???
As Dr. Lockwood is employed by a major oil company, might he be slightly biased in his opinion and recommendation???
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/ Caramel
