Oil Drain Intervals

How to maintain engine performance and maximize useful service life through optimizing oil drain intervals.

Each of the oil manufacturer representatives advise against using motor oil additives and treatments. They point out that oil companies have invested millions of dollars formulating engine oils that meet or exceed industry standards and OEM requirements. “By adding motor oil additives and treatments, you change the formulation of the engine oil and risk deteriorating its performance,” McGeehan of Chevron says. “It will also likely void the engine oil marketers warranty as well as the OEM’s warranty because it negates any performance claims of the oil and no longer meets the OEM’s recommendation.”

“Know what your engine manufacturer has to say about the use of aftermarket additives,” adds Betner of Citgo. “It is not just a simple matter of adding more to the ‘good stuff’ already in the oil. You may very well be taking the oil backwards or at the very least violating the certification for that oil formula.

“Think of adding something to the oil as going to the doctor and getting a prescription,” he says. “On the way to the pharmacy, you decide that the doctor really did not choose enough or even the right type of medication. You buy some off-the-shelf medication and take it along with your prescription. Do you really know the outcome of that decision?”

If there was something that needed to be added to the oil, the engine oil manufacturers would offer that option either in terms of an extra additive or a performance upgrade, Betner goes on. “The best proven option is to buy the premium performing product to start with and you’re safe all the way around.”


Oil filter selection ought to be based on the recommendation of engine and filter manufacturers. Key considerations in selecting oil filters are efficiency, capacity and service life, says John Enright, senior product manager, heavy duty filters, Purolator.

“Efficiency indicates the ability or effectiveness of the filter to remove contaminants, which directly affects engine wear and overall life of the engine,” he says. “Capacity determines how much contamination a filter will hold - an important consideration in determining oil and filter change intervals. Service life is determined by both the efficiency and capacity of the filter and will depend on how well it traps and holds contaminants.”

Enright explains that filter performance can be affected by such variables as operating environment, engine type (EGR vs. non-EGR), type of lubricating oil, fuel quality, type of driving and even climate. “Today’s EGR (exhaust gas recirculation) engines help reduce NOx emissions but can reintroduce soot to the combustion process compromising lubricating oil quality,” he says. “Where there are broad climate variations, there is the possibility of added condensation in the oil.

“At Purolator, we recommend following and adhering to OE oil and filter change intervals. However, for those operators considering longer service intervals, we recommend utilizing a preventive maintenance program with oil analysis being a key component, and auxiliary filtration if necessary. Probably the most effective auxiliary filter unit in controlling soot in EGR engines is the centrifuge.”


Engine maintenance has an effect on oil life and performance as well. A poorly tuned engine will have higher fuel consumption, greater thermal loading and create more soot, among other things, says Chevron’s McGeehan. This leads to increased oxidation, nitration and soot loading of the oil. This, in turn, leads to more deposits, corrosion, wear, potentially stuck rings, diesel particulate filter plugging, etc. Furthermore, such maintenance issues can lead to premature contamination and deterioration of an engine oil and ultimately compromise the protection of an engine’s critical parts.

Restrictions to radiator air flow and not maintaining the coolant system can result in higher engine temperatures and reduced oil life, Shell’s Arcy adds. Up to 50 percent of engine oil lubricated failures are caused by improper cooling system maintenance or are related to cooling system problems, notes Citgo’s Betner. Air induction maintenance and maintaining proper air filter integrity is also critical to controlling dirt contamination in the engine oil.

Fuel system maintenance can lead to excessive fuel dilution or improper fueling injection into the combustion process, he continues. This can lead engine oil dilution, excessive soot loading and increased fuel consumption, all of which can be costly.


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