984 K Road
Minden, Nebraska 68959
308/832-22OO



LEAD CONTENT

Lead content in grams of lead per gallon:

Until January 1986, regular auto fuel contained a maximum of 1 gram of lead per gallon. It now contains a maximum of 0.1 of a gram per gallon. No minimums were established under the new lead content regulations so it is possible to obtain regular with the same lead content as unleaded, or .001 of a gram per gallon.

In view of this, we recommend that you use one tank full of 100LL every 75 hours to replace lead on the valve seats. Lead builds up on these parts and will not be "washed off" the first time you use an unleaded fuel. By using 100LL only every 75 hours, you will be supplying adequate lead for these parts. Also, during break-in following an overhaul or replacement of a cylinder, you should use 100LL for 25 hours in order to supply lead during the break-in process. A mixture of 75% unleaded and 25% 100LL yields a lead content equivalent to 80/87 octane avgas (0.5 gram per gallon). Radial and Franklin engines should use this mixture at all times because they are much more dependent on lead for lubrication.

Burning an occasional tank of 100LL should not be necessary if the valve's, guides and seats were constructed in accordance with the latest specifications. In view of the fact that 100LL is eventually slated to be replaced with an unleaded high octane fuel, anyone facing an engine overhaul would be well advised to seek out hardened, newer spec parts. These parts are not available for radial engines as far as I know. However, most horizontally opposed engines can be rebuilt with hardened parts if you seek them out.
ASTM D-439/D-4814

Auto fuel STC's were developed using fuel blended to ASTM specification D-439. D-439 has now been superseded by D-4814. The difference between the two specs is in the test methods outlined. D-4814 added test methods to be used at the refinery for oxygenates but does not require the addition of oxygenates. EPA regulations require the addition of oxygenates in some regions of the country, as do some local regulations. Reformulated gasoline (RFG) contains oxygenates and although there are other differences between RFG and standard gasoline, the percentage of oxygenates are what we, as pilots, need to be primarily concerned with.

The most widely used oxygenates are ethanol, Methyl Tertiary Butyl Ether (MTBE), and Ethyl Tertiary Butyl Ether (ETBE). At this time, ethanol cannot be legally or safely used with the STC's. Fuel containing MTBE or ETBE is acceptable. Therefore fuel blended to D-439 or D-4814 without alcohol, is acceptable and legal for use with the STC's. If your state does not require compliance to these specs, it does not necessarily mean that your fuel does not comply. Since most states require compliance with these specs, it would not be cost effective for the oil companies to lower their standards in those few states not requiring compliance. Generally, any fuel produced by a major manufacturer is blended to D-4814.

Fuel in countries such as the Philippines and Sri Lanka meet D-439. One can expect most of the fuel produced on the planet to meet this specification even if it is produced in a country (or state) not requiring compliance specifically with D-4814. There really is no need to require it, selling off spec fuel would not be cost effective for those who are refining and distributing it.

The following states require compliance with D-4814 in whole or in part or require critical specifications values per ASTM D-4814.

Alabama Delaware Indiana Mississippi Oklahoma Virginia
Arizona Florida Iowa Montana Rhode Island Wisconsin
Arkansas Georgia Kansas Nevada South Carolina Wyoming
California Hawaii Louisiana New Mexico South Dakota
Colorado Idaho Maryland North Carolina Tennessee
Connecticut Illinois Minnisota North Dakota Utah

Only eight states require compliance with the aviation fuel spec. D-910, and there is no federal requirement for aviation fuel to meet the spec.

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