Replacing Lead in Older-Engine Fuels

Question: My 1971 Continental is in almost-new condition, except that it was designed for high-octane leaded fuel, which is no longer available. My gasoline station recommended Sim-U-Lead, made by Sta-Lube. Is this product better than nothing at all? Could it be harmful?--W.L.

Answer: Sim-U-Lead is among the first barrage of additives that are supposed to take the place of lead in gasoline for older engines. Many of these products, including Sim-U-Lead, use as their active ingredient “Powershield,” which is made by the Lubrizol Corp.

The reduction of lead content in leaded gasoline has caused great concern among owners of older cars, farm equipment and motor boats. These older engines, built before 1971, have valve seats that depend on lead for protection and lubrication.

The federal government has ordered lead content in gasoline sharply reduced, and today it amounts to a mere .1 gram per gallon, down from 1.1 grams as recently as one year ago.

The Lubrizol product is not sold at retail but is packaged by a number of formulators into retail products. The company is currently seeking approval by the Environmental Protection Agency to have the substance added to gasoline in bulk.

Powershield uses sodium, a metal, as a substitute for lead, which is also a metal. In tests by Lubrizol, sodium appears to behave in largely the same way as lead, according to Dr. Thomas Johnston, director of fuel additives at the company. Both metals form a thin layer over the valve seat, which reduces wear.

Lubrizol believes about 10 to 15 times less sodium is required for engine protection than was the case for lead. At recommended concentration, Powershield would be diluted with gasoline to 8 parts per million. By comparison, the .1 grams of lead in gasoline amounts to 34 parts per million.

In recent tests conducted by the company, which have not been audited or verified by outside sources, the Lubrizol found that current lead content can lead to rapid engine damage, especially in farm and marine engines. Such motors are usually run under heavier loads than car engines.

So far, it does not appear that any manufacturers have introduced a tetraethyl lead that consumers can add to their own gasoline. The product is so toxic that some producers are afraid to put it in the hands of consumers. Lubrizol believes that its sodium formulation is safer.

Incidentally, lead also is used to boost octane or anti-knock quality to gasoline. Powershield does not boost octane. So, if your old engine needs a high-octane fuel, you might consider using an unleaded premium gas with a lead substitute. If your engine does not need a high-octane fuel, then a leaded gasoline can be used with a substitute.

The cost of a bottle of Sim-U-Lead is about $2.50, which makes it a costly proposition. If the directions are followed, the cost amounts to more than 10 cents per gallon. If the EPA approves the product for bulk sale by gasoline stations, the cost could come down to less the 1 cent per gallon.

Here’s an update for owners of Ford Ranger trucks that have had problems with drive line clunking noises. Ford has traced the noise to binding on the drive shaft spline. In the 1987 model year, the company will impregnate Teflon on the spline to eliminate the clunking. After getting the improvement into the new trucks, Ford plans to make the fix available to current Ranger owners on a warranty basis. It could take up to a half year, however.