Report # EPA 1-2008

Aviation Oil Lead Content Analysis

January 2, 2008

Todd L. Petersen

Petersen Aviation, Inc.

Minden, Nebraska

  HYPERLINK "mailto:todd@gtmc.net"  todd@gtmc.net 

308-832-2200

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:   HYPERLINK
"http://avlab.com/analysis/login/default.asp" 
http://avlab.com/analysis/login/default.asp   The Customer Code is
“ptrav”.  Insert “ptrav-a” 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 0-320-D2J-160hp engine with 100 hours reported
since the previous oil change showed the highest lead content at 10286
ppm.  Sample G, a Lycoming 0-235-L2C, 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 0-320 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 by-products both in the exhaust blow-by 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 100-hour maintenance rotation and will therefore
change oil at 100-hour intervals because it is convenient.  The standard
recommendation however is 50-hour interval oil change and filter
replacement for engines using a full-flow filtration system and 25-hour
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	0	0



