Embroiled in Oil

Embroiled in Oil
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from Hemmings Classic Car

November, 2010 - Jim Richardson

Let's talk about oil, that odiferous muck from the netherworld that makes our modern world possible. Without it, most of us would be walking to work, and our roads would be paved with an amalgam of dust and horse excreta.

Oil is a hot potato these days, with the recent Gulf spill, and I don't want to talk politics. But there are some things every classic car buff should know about the automotive products that we make from the stuff. Things like: Our old cars were designed to run on it and be lubricated by it. Sure, you can burn alcohol or propane or even wood, but those don't work as well as gasoline.

As an example of what I am talking about, propane produces less power and more heat in your engine, and you will have to carry a big pressurized tank of it to power your car. And alcohol provides only 70 percent of the energy of gasoline, so you will need to burn nearly twice as much of it to get from A to B.

Hot rodders have been running alcohol forever, as have the Indianapolis racers, but that is because you can increase the compression ratio of the engine for racing, and because alcohol is less likely to explode in a crash. It's not because it's a great alternative to gasoline. Indy cars have little engines, but only get about 1.5 miles per gallon.

There are myths surrounding gasoline that old car buffs should know about, too. To begin with, it doesn't matter which brand of gas you run in your car. That's right: It's all refined to SAE standards, and the cut-rate stations buy the excess from the few big refiners--so at the cut-rate station, you get the same fuel you would at the full retail station.

The second myth about gasoline is that high octane ratings help an engine that does not have high-compression cylinder heads. Not true. All octane boosters do is prevent detonation, and most old cars--other than the high-compression, high-performance muscle cars of the late Fifties, Sixties and early Seventies--don't have a problem running low-octane fuel.

As an example, my 1940 Packard runs just great on unleaded gas, as does my 1955 Chevy. In fact, the Packard would be fine with 76-octane fuel. I know this because Union 76 gasoline was named that in the 1930s, not out of patriotism, but to tout their 76-octane gas, which was hot stuff back then. Check with your mechanic, and then try regular gas in your classic. If it doesn't ping or knock, and you don't drive it hard, it'll be fine.

Engine oil is a different story. That's because since 1975, when modern catalytic converters debuted, refiners have eliminated the sulfur and zinc compounds in automotive oil because these ingredients clog converters. To make it work, the carmakers have gone to roller tappets in their valvetrains. You see, the zinc sulfur compound provided a sacrificial metal that kept flat-tappet cams from galling, and pistons from scuffing and wearing out. It also filled in pitted bearing surfaces and made engines last longer.

I found out about this the hard way when I put a mild cam in a 1957 Chevy straight-six a while back, in an effort to boost performance. The engine ran great until the lobes on the cam went flat. They couldn't survive without those zinc dithiophosphates that engine oil had in it back when our classics were built.

So how do you deal with this problem? There are three ways. You can add oil additives that include ZZDP. It's recommended for everything from Model T Fords to vintage muscle cars. Another alternative is to do what I do and use specially formulated oil that contains plenty of zinc-sulfur compound.

Finally, you can help your pre-catalytic converter engine survive by using oil intended for diesel trucks. The powers that be are busy taking the sulfur-zinc compound out of it, too, but there's still enough at this point to help your engine live a bit longer. You can get diesel engine oil at most auto supply stores or at the nearest truck stop.

I hope this advice helps keep your classic healthy. Contact me at jameshr106@aol.com if you have questions.


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