Death Of A Classic Part II

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In addition, another factor is working to buy time for both petroleum refiners and their customers: A "lead banking" provision, enacted by the EPA in March of last year, allowed gasoline manufacturers to produce, through 1985, leaded fuel containing fewer grams of TEL per gallon than required. The "credits" thus earned can be applied to production after January 1986, when the really stringent standards went into effect. In practice, that means that much of the leaded gasoline sold today may legally contain 0.20 or 0.30 gplg . . . a level that, depending upon the refiner, may not drop to the mandated 0.10 gplg until 1988.

SECOND-GUESSING THE FACTS

The truth is, no one can predict exactly what impact the EPA's course of action may have, because there are too many variables. But there are steps an individual can take to lessen the effect of unleaded fuel on an engine designed for leaded gasoline.

According to the EPA, Amoco Oil Company, and a number of professionals knowledgeable in the automotive field, normal driving with unleaded fuel should pose no serious problems for a car used to running on leaded. But under "abnormal" conditions (which can be as common as trailer towing, heavy loading, or fast driving) valve seat deterioration can and does occur . . . due to high combustion temperatures and physical wear caused by the valve grinding hard abrasive oxide particles into its comparatively soft castiron seat. Eventually the exhaust valves, the seats, and the valve guides are worn enough to cause dramatic loss of compression.

Moreover, unleaded fuel, though producing fewer hydrocarbons in combustion than leaded gasoline, forms carbonaceous deposits in the absence of TEL that have a greater heat capacity than do lead deposits. Under extreme operating conditions, this can cause pistons to erode or collapse, since it affects their original hardness. Even in the course of normal driving, extended use of unleaded gasoline can raise an engine's octane requirement.

How does all this relate to you as the owner of a leaded-fuel engine? If you're not too hard on your equipment, you can take your chances and use unleaded . . . while checking for telltale signs of valve recession such as frequent exhaust valve adjustment or dwindling compression. If you don't like the odds, write the engine manufacturer to determine if your model and serial number series has been equipped to operate safely on unleaded fuel.

Engines designed to run on leaded gasoline can be adapted, by degrees, to accept the no-lead substitutes. Before even touching a wrench to your powerplant, you might consider switching to a straight-grade, moderatedetergent premium oil with some degree of ash content. The "dirty" ash coats the surfaces of the valve face and seat, reducing the physical wear at those critical points. Avoid using ash-free or synthetic oils, since they tend to keep the contact surfaces clean and thus subject to abrasive grinding.

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