Dear Car Talk: Ever since Smokey Yunick recommended it in the 1970s, I’ve been using synthetic motor oil.

Now, along comes something called a “synthetic blend.” Nobody can tell me the ratio of synthetic oil to regular oil in a synthetic blend. Can you? — Ron

Nope. The oil companies don’t make that information available. Perhaps it’s not required to be disclosed because it comes under the guise of trade secrets. Or maybe it just falls under marketing-driven B.S.

Here’s my guess: Most engines call for synthetic oil now. It’s clearly superior to the dinosaur-based stuff we’ve used since shortly after the wheel was invented. Synthetic oil lubricates better and lasts about twice as long. And most companies that manufacture — and, more importantly, have to warranty — engines, insist you use it.

But it is a bit more expensive than conventional oil. So, in order to sell something at a lower price-point for, what’s the term? Cheapskates! They came up with this concept of “synthetic blend,” which is a mixture of dinosaur oil and synthetic oil.

Is it any better for your engine than pure conventional oil? I have no idea. If it is, it probably depends on how much synthetic is in the blend.

And since they won’t tell us that, I think an educated consumer is wise to assume that it’s a very small amount.

I mean, theoretically, they could put a teaspoon of synthetic oil in a quart of conventional oil and call it a “blend,” right?

I have no idea if it’s that little. But the fact that they keep that information secret suggests they’re not particularly proud of the percentage of synthetic oil in their blends.

So, I’d absolutely recommend sticking to a full-synthetic oil, Ron. I mean you wouldn’t buy partially pasteurized milk, right? Or partially galvanized steel? So don’t buy slightly synthetic oil.

Synthetic is a little more expensive, but when compared to the cost of major repairs to your engine, it’s dirt cheap, really.

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