Since synthetics are created in a lab and contain additives to keep your engine in tip-top shape, they're more expensive than traditional mineral oils. How much more? Try six to 10 times the price, according to Cantiz at Royal Purple.
However, there are ways to get some of the benefits of synthetics without breaking the bank. For those who live in climates with noticeable seasonal changes, you could use a synthetic oil in the winter months when your engine is under the most stress from cold starts, and then switch to a mineral oil in the summer, when its more random molecular structure will remain warm and easy flowing.
For modern cars, mineral oils are good, blended oils are better and synthetic oils are the best. But if you've got a 30-year old car with original seals, the truth is, no oil or additive is going to help much.
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