Dear Car Talk:

I really enjoy reading your column. You recently answered a question about synthetic oil, and you recommended using it. I've used synthetic oil for years, with great results. What about using oil additives? They claim to reduce friction and extend engine life. I have used Slick 50 for years, and have now started to use a German product, Moly Lube. Do you recommend products like these? -- Tom

Moly lube is an engine additive? I always thought it was one of those "adult products." My wife's going to be really upset when I break the news to her.

Do I recommend oil additives? No. I think they're all unnecessary.

The grade of motor oil recommended by your manufacturer, in general, has all the friction-reduction properties you need. And full-synthetic motor oils are even better and, more importantly, hold up better and last longer.

I don't know anything about Moly Lube's claims. I do know that Slick 50 paid $10 million to settle Federal Trade Commission charges of false and unsubstantiated advertising some years ago. I also know, in general, that over the years, many people have gotten rich selling unnecessary potions, additives and elixirs to the gullible auto-owning public. My wife reminds me of that every time I splash some MiracleGro on my ever-widening scalp.

Seriously, the proper oil for your engine (and I do like synthetic), changed regularly, is all your car needs to reduce friction and delay wear and tear.

If you want to do more to help prolong the life of your engine, I think the most effective thing you can do is change the oil a little more often than is recommended. So if the synthetic oil calls for a change every 10,000 miles, change it every 7,500 or 8,000 miles.

And just as importantly, drive gently. Jackrabbit starts and hard acceleration do more to shorten the life of an engine than just about anything -- short of lending the car to your teenaged progeny. Good luck.