- Lubricant consumption: While excessive lubricant consumption may indicate other problems, all other things being equal, the greater the lube consumption and replenishment, the better the chances for an extended drain. Any time you add more lube, it’s being renewed or “sweetened,” including beneficial additives.
- Lubricant quality: Some lubricants are simply more effective than others for particular applications, whether due to better base stock or to superior additives.
- Fuel economy: Fuel economy is a direct indicator of how much acid, unburnt fuel, fuel dilution, soot, and other contaminants are developed and placed into the oil. An engine that consumes more fuel is doing more work, which can cause the oil to degrade faster. Most engine manufacturers have information that uses fuel economy to indicate what sort of duty cycle the engine is operating and therefore what potential there is for an extended drain interval.
- Duty cycle: Duty cycle is a set of factors that indicates how hard the engine is working. For vehicles making long-distance trips where optimum road and engine speeds can be maintained for long periods, there is generally less stress on the oil, and longer drain intervals can be achieved.
- Heat: Excessive temperature is an enemy of all engine oils, promoting oxidation and other forms of lubricant degradation.
- Contamination: Contaminants will ultimately render a product ineffective as a lubricant. Type and degree of filtration can influence and prevent this condition, depending on the nature and cause of the contamination and the composition of the filter.
- Equipment usage: How a particular piece of equipment is used plays an important role in lubricant drain interval and affects all of the above parameters.
