and are proportional to fuel air management; turbocharged engines tend to
burn cleaner than naturally aspirated engines. Filtration will have direct
effects on soot and dissolved particles and can be effective at increasing oil
life. Since lubricating oils are products of base oils mixed with chemical
additives it becomes painfully obvious that the failure of the base oil or the
depletion of additives will result in condemnation of the oil. Simply put, oils
are unique when compared to each other; even if two synthetics are
compared, the choice of synthetic base oil and the quality and amount of the
additives can produce widely varying finished products.
Oil life is best determined utilizing used oil analysis and then evaluating
the remaining oil life based upon the results of a given analysis. Some oil
companies, like Mobil and AMSOIL have amassed significant data through
oil analysis that enables them to make categorical recommendations for
longer drain intervals. It is improper to assume that because you are using
synthetic oil it automatically has an extended drain interval. Some major oil
companies (Valvoline is one) are on record as saying that their synthetic oil
has the same additive package as their petroleum; so, the additives in their
synthetic oils deplete just as quickly as their petroleum oils.
Advantage: Synthetics (varies between synthetic manufacturers)
Cost: What is the real cost to use synthetic oil compared to petroleum? To
correctly assess cost it is necessary to differentiate between price and cost.
What you pay for an item is the price; how the price is distributed with
respect to product utilization over time is cost. For example, if you pay $160
for an 80,000-mile radial tire, then that is how much you pay to purchase the
tire. To determine the cost, you have to distribute the $160 over the 80,000
miles; this determines the cost per mile to use the tire. This method allows
the direct comparison of products that are priced differently, but that have
variable life expectancy. Calculating cost is a mixed bag when comparing
synthetic and petroleum oils. Not all synthetic oils are designed for extended
oil drains and some petroleum oils will perform much better than others.
Comparisons are best done on a case-by-case basis. In general, most any
synthetic will run longer between oil drains; however, only a select few are
designed for very long drain intervals. For the synthetic oil to be equal or less
costly, it must have approximately three times the drain interval of a given
petroleum oil. There are other, indirect cost benefits to synthetic oils,
including improved fuel economy and superior lubrication that results in less
maintenance. One unheralded feature of synthetic oil is insurance: by that I