Old Cars, Old Oil

Eric Peters is the resident car expert on LewRockwell.com.

Recently, he wrote an article on maintaining old cars. He spoke of his 1976 TransAm.

I still have all the original paperwork, including the service schedule. It tells me to change the oil once every 7,500 miles or six months — whichever comes first. Well, it’ll take me at least a decade to rack up 7,500 miles — since the car only leaves the garage occasionally. I drive it about 500 miles each year.I should probably change the oil more often than once every ten years.

But once every six months? Given maybe 250 miles or so of driving? That seems . . . wasteful.

And is.

Expensive, too. Oil — the good stuff — costs more than $10/quart and the old Pontiac takes six. Plus a filter. Plus tax — and it’s about $75 to change the oil . . . myself.

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But the oil does need to be changed at some point. So — what point? I split the difference and do it once a year, regardless of the mileage. Even if the car has barely been driven at all.

In fact, precisely for that reason.

Not because the oil wears out. Oil is pretty much eternal, actually. But it does become diluted and contaminated, especially if it’s sitting in the crankcase of an old car with a carburetor perched on top. These invariably leak gas, which finds its way into the crankcase, where it dilutes the oil. And gas is not a lubricant. It is a solvent. This is not what you want mixed in with your lubricating oil.

There is also condensation — water — that mixes with the oil. Also not a lubricant. And, sludge — the bane of lightly/rarely-used cars. It can gum up the works, including the oil pump pick-up, which is usually located in the bottom of the oil pan. If the intake screen gets glutted…

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