by Robert Sanborn on Mon, Jun 25, 2007, who was a member of the STLE Society of Tribologists and Lubrication Engineers for 15 years.
It is obvious that the oil should be changed before its contaminant level reaches the point where engine damage can result. It is difficult, if not impossible, for the individual motorist to determine when the contaminant level is too high.
Oil analysis can often be used to determine contamination and wear levels. This information is important for motorists to determine if an additive has actually reduced wear, or if your engine is on its last legs. SFR often recommends doing an oil analysis to determine the amount of contamination, or the amount of wear reduced since adding an additive. SFR offers this service through an independent oil analysis company, WearCheck. Since the oil analysis reports are technical SFR recommends calling in after you receive your report so that we can guide you through the report.
For this reason automobile manufacturers recommend oil change at a certain time interval not to exceed a maximum mileage limit, whichever comes first. These change recommendations vary from year to year and from manufacturer to manufacturer. Recommended intervals and mileage limits also vary with the type of service under which a car operates. More frequent changes are always recommended for severe service.
What is severe Service?
Both the car manufacturers and the petroleum industry are aware that some types of car operations are more severe than others—that such operations place greater demands on the motor oil and call for more frequent motor oil changes. It is for this reason that the car manufacturers give two recommendations for oil changes in their owners’ manuals—one recommendation is for what might be described as ideal service operations and the other recommendation is for severe service operations.
Ideal service operations consist of relatively high-speed driving on paved roads in dust-free areas. The maximum oil change recommendations in car owners’ manuals apply to this type of driving. They do not apply to severe service operations.
Severe service operations include the following: a. Trips that are less than 10 miles (16.09 kilometers). b. Driving in dust or sand. c. Cold weather, which prevents full engine warm-up. d. Idling for extended periods. e. Pulling trailers. f. Operating in any other heavy-duty and severe service.
Severe service operations represent the type of driving done by most motorists. One of the most frequent and severe types of driving is short trips with many stops and starts. Under such conditions engines do not reach normal operating temperatures, particularly in cold weather. For his or her protection the motorist should recognize these severe service operations and follow the recommendations of the car manufacturers.
Just as oil changes are desirable at regular intervals, it is equally important that oil filters should be changed in accordance with the car manufacturer’s recommendations.
It should be pointed out that oil change recommendations are not retroactive and do not alter the recommendations for earlier model cars. This is important, because in recent years oil change intervals have generally been extended. Applying such schedules to older cars could lead to serious problems.
With newer synthetic oil can I have extended drain intervals?
Many synthetic oil sellers state that you can extend drain intervals twice as long or even longer—sometimes much longer—but that can be dangerous. Studies have shown that synthetic oils are refined and can withstand longer use than petroleum motor oils. However, it’s much more complex than buying a synthetic and automatically doubling your drain interval. Additives get used up as they disperse, fight oxidation, foaming, corrosion, wear etc. But worse than that is what happens if you get an unusual amount of silicon in your air filter, or a fuel pump leaks and you experience fuel dilution. If you change your oil regularly—even with synthetic—you would have a chance to catch one of the problems I just mentioned and do no serious damage. However, if you just start doubling you drain interval or going longer you could experience severe engine damage That is why most all industrial/commercial companies change their oil and fluids based on condition and not by time. Condition is monitored by oil analysis that can detect a blown head gasket, other contaminates such as dirt and fuel, wear etc. Extending your drain interval by use of a synthetic is fine but use prudence.