1. "You can't use it in older engines"The age of the engine has nothing to do with lubricant selection, but the engine manufacturer's recommendation does. It's true that older engines may leak or burn...
The age of the engine has nothing to do with lubricant selection, but the engine manufacturer’s recommendation does. It’s true that older engines may leak or burn the expensive synthetic product, but that is an engine condition problem, not age. In most cases synthetics can be freely interchanged with mineral-based oils with no ill effects, provided the grade and viscosity fall within the engine’s specifications.
2. “Once you start using synthetics, you can’t go back”
There’s no difficulty in returning to the engine appropriate grade and viscosity of oil, but the real question is, why? The switch to synthetics confers definite advantages in cold start lubrication and high-temperature operating regimes so why go back? For an increasing number of high-performance applications, synthetics are factory-fill, and should always be used. Again, the engine manufacturer’s recommendation is the rule to follow.
3. “Synthetics can damage some engines”
No engine was ever damaged by using the correct grade and viscosity of quality lubricant. This myth may have started in the early days of energy-conserving practice, when some technicians substituted 5W synthetic multigrades in engines that specified 10 or 20 weight oils. Synthetic oils are superior in many regimes, but they won’t alter bearing clearances. The API “medallion” is still applicable, so if the engine needs SH, or SJ, the engine should be so equipped.
4. “Synthetics aren’t compatible with conventional oils”
At one time, there was some truth in this one. Some early synthetics carried additive packages that did cause problems when mixed with mineral-base oils, but the problem wasn’t related to the synthetic lubricant carrier, and isn’t a problem today.
5. “It’s really the same stuff as conventional oils”
See above. Synthetics have definite advantages over mineral-base engine lubricants under extreme operating conditions.
6. “Synthetics cause oil leakage”
A persistent rumor about synthetics suggests that they dissolve internal engine varnish and sludge that internally dams worn seals and gaskets. In reality, quality detergent oil, changed regularly, should keep an engine clean regardless of the origin of its base stock. Switching to lighter weight synthetics from specified heavier multigrades (usually to 5W from 10W) is common in showroom-stock type road racing, and frees a little power, but isn’t recommended for street vehicles. And if leakage is an issue, there are larger issues than premium engine lubricants.
7. “Synthetics eliminate the need for additives”
Aftermarket oil additives are a hot-button issue, regardless of the type of engine lubricant. While there’s no hard and fast rule regarding the “need” for supplements, reputable synthetic or non-synthetic engine oils can carry additives equally well.
8. “Synthetic pricing is a rip-off”
Synthetics are more expensive that conventional engine oils for several reasons, the most important of which is the method of production. Synthetics base stocks are built-up in series of chemical reactions, where mineral base stocks are removed as one fraction of the petroleum distillation process, among others. Synthetics are more expensive to produce. Less tangible factors are lower consumer demand, fewer companies with synthetic production capability and the current price of oil and gas in world markets.
9. “More frequent oil changes are as good as using synthetics”
It’s true that no one ever hurt an engine by changing its oil too frequently, but it’s also true that the manufacturer’s recommended interval is the one to follow. While some synthetics can allow extended drain intervals, in many cases (e.g. Stop and go driving and other forms of “severe service”) it’s not breakdown of the carrier lube that drives the need for change, but consumption of the oil’s additive package, and the need to get suspended contaminants out of the engine.
10. “Average drivers don’t need synthetics”
Perhaps true, except that exceptional drivers follow scheduled maintenance, warm up engines properly, and ask for premium brands. The driver that cold starts at -40 degrees with a blast to the redline, then drives off, may need the synthetic more than the Porsche owner. And if oil changes are spotty or inconsistent, synthetic might be a form of “insurance” in the customer’s mind. Just be sure to recommend that the manufacturer’s drain interval is followed, whether synthetic or conventional oils are used.