Report # EPA 1­2008 

Aviation Oil Lead Content Analysis

January 2, 2008 

Todd L. Petersen 

Petersen Aviation, Inc. 

Minden, Nebraska 

todd@gtmc.net 

308­832­2200
In November and December 2007, samples of used aviation oil were collected at three Nebraska airports. The 

samples were taken from airplanes using 100LL exclusively. Ten samples were obtained and subsequently 

analyzed for lead at the end of December. Sample eleven consisted of new, unused Aeroshell 100W. Aviation 

Labs in Kenner, LA did the analysis. Results of the analysis may be reached on the Internet by going to: 

http://avlab.com/analysis/login/default.asp  The Customer Code is “ptrav”.  Insert “ptrav­a” for engine serial 

number.

Results of the analysis are shown on the attached graphs. The oil is delineated by engine type, number of hours

on the oil since the previous oil change, and by the engine sump capacity.

Sample J, from a Lycoming 0­320­D2J­160hp engine with 100 hours reported since the previous oil change 

showed the highest lead content at 10286 ppm. Sample G, a Lycoming 0­235­L2C, also with 100 hours on the 

oil, tested out at 5797 ppm. The engine with the least amount of lead was sample C, a Lycoming 0­320 with 20 

hours on the oil. This sample tested out at 1726 ppm. The unused oil contained only 226 ppm of lead.

Lead and lead by­products both in the exhaust blow­by gas and in raw fuel eventually work their way into the 

oil. Variations in lead content of the samples discussed herein may be attributed to a number of factors. How 

the pilot leans the mixture and when has an impact on how much lead is retained within the engine as opposed 

to being ejected through the exhaust. Elevation and density altitude are among the factors that influence how a 

pilot leans the mixture.  Location within the flight envelope, climb, cruise, decent for landing, also dictate 

leaning procedures. These factors change constantly. Mixture and throttle settings used between landing and 

engine shutdown and during engine warm up before flight, also influences the amount of lead retained within an 

engine and therefore the amount of lead that ultimately is transferred to the oil.

Some pilots use a gasoline additive made by Alcor called TCB to reduce spark plug fouling when using 100LL. TCB laden fuel therefore contains more lead scavenger than what is included in a standard gallon of 100LL. Hence it is expected that less lead would be retained in an engine consuming this additive. It is unknown 

whether or not any of the oil sampled was used in engines consuming TCB laden 100LL.

It should be noted that samples J and G, are both flight school airplanes. Student pilots are considered less

likely to properly lean the engine since they are still learning. Students will also be shooting numerous takeoffs

and landings and for the most part, this will be done with the mixture full rich. Flight schools frequently have 

their airplanes on a 100­hour maintenance rotation and will therefore change oil at 100­hour intervals because it 

is convenient. The standard recommendation however is 50­hour interval oil change and filter replacement for

engines using a full­flow filtration system and 25­hour intervals for pressure screen systems.

Engines originally rated on 80/87 octane will show increased amounts of lead in the oil when they are 

consuming 100LL. More frequent oil changes are recommended for these engines. Samples B, C, D, E, and H 

came from engines originally rated on 80/87 octane. The first four of these samples have relatively low hours

since the previous oil change and this might be attributed to the pilots deliberately conducting more frequent oil 

changes as per the recommendations. Doing so is also intended as a means of reducing corrosion inherent in 

engines that are not operated frequently.

Respectfully submitted. 

Todd L. Petersen 

Petersen Aviation, Inc
Engine Model 

Lead ­ Parts per 

Million 

Hours

Sump 

Capacity 

­ Quarts

A    Cont IO‐360 2453 50 8 

B    Cont 0‐300 3605 25 8 

C    Lyc 0‐320 1726 20 8 

D    Lyc 0‐320 2911 20 8 

E    Cont C85  3747 21 4.5

F    Lyc IO‐360  2017 40 8 

G    Lyc 0‐235 L2C  5797 100 6 

H    Cont 0‐300 4456 40 8 

I    Cont IO‐550  5536 50 12

J    Lyc 0‐320 D2J 10286 100 8 

K    New Unused 

Oil 226

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