Car Talk

January 1990

Dear Tom and Ray:
First there was Gasoline. Then there was Regular and Unleaded. Now there's Unleaded and Super. It so happens that we have an elderly Olds that we use to pull our horse trailer. The book says to use Regular gas in it. Also, there are various older engines, including chain saws and lawn mowers, that say to use Regular gas only. What are we supposed to do?
Ivan and Barbara

Beat up old car

TOM: When your Oldsmobile manual says to use Regular gas, it means leaded gas. For very sound environmental reasons, you can't get that anymore, so you're out of luck. The lead was there to protect the valve seats. Without it, they'll eventually recede--perhaps clear through the cylinder head and up through the hood! But that may take years, so don't worry about it.

RAY: When it does happen, have those lazy horses pull the car. I don't know how all of these horses fooled us into pulling THEM around. Not too long ago, they used to pull US around. All over the world, there are horses pointing at pictures of horse trailers and laughing til they have tears in their eyes.

TOM: Seriously, if and when the valve seats do recede, you'll have to rebuild the cylinder head. As for your chainsaw and lawnmower, they call for Regular gas because it's lower in octane than Super. High octane gas burns too hot for these machines and would eventually damage them. 87 octane unleaded (regular) is fine.

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