Shade Tree Answer Man: Which Oil is Right for my Car?

Some of Terry Longsworth's colorful collection of antique motor oil cans.04 Cos Gas Collector
Some of Terry Longsworth's colorful collection of antique motor oil cans.04 Cos Gas Collector /
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What about synthetic oil?

Natural, or conventional oil, is refined from crude oil. But any fossil fuel has its limitations. Refined oil products tend to gel or freeze in extreme cold, and their supply is limited.

Eventually we will have pulled all of the dead dinosaur goo out of the earth and no longer will be able to manufacture the array of gases and liquids that fuel and lubricate our machinery.

That’s where synthetic oils come in. Available commercially for the past 50 years or so, these lab-made oils have a more consistent molecular structure than their natural counterparts.

This ensures a more even distribution throughout your engine’s passages and overall better performance. Blended oils are a combination of the two, and give some of the benefits of a synthetic while saving you a couple of dollars over a full synthetic.

So do you need synthetic or blended oil? Again, if your owner’s manual indicates that you do, you definitely do. If not, it’s up to you.

Newer engines will benefit from the technology in a blended or synthetic oil, but in the end it may not make enough practical difference over a car’s lifetime to justify their cost.

How about high-mileage blends?

These formulations are largely a marketing strategy to separate you from a few extra dollars per oil change, but in limited circumstances they may help. A little.

High-mileage oils are usually synthetic blends with additives like sealers and detergents, which presumably will help extend the life of your older engine.

The hard truth is, if your engine is sprouting internal fluid and pressure leaks, no amount of magic liquid or foam or prayer is going to put off that impending rebuild (or NPR donation) forever.

Most synthetic blends will give you the same level of engine protection at a lower price than the high-mileage formulations, just without the braggadocious labeling. So leave that “75,000+” bottle on the shelf and put the savings in a coffee can for the day your oil pressure drops to zero.