ASL CamGuard Lab Tests
Methodology, Procedures, And Results

New* Corrosion Testing Of Aviation Oils

Corrosion testing of four oils with and without CamGuard was performed using the latest humidity cabinet testing procedure the DIN 50017. This is a worldwide reference test procedure showing both greater repeatability, test to test, and greater reproducibility, lab to lab, than the ASTM 1748.

The oils tested were 20W-50 semi-synthetic (SS), 15W-50 semi-synthetic (SS), 20W-50 AD and W100 AD. Both semi-synthetic oils have corrosion inhibitor packages. This test is cyclic and uses distilled water. One cycle is 24 hours (1 day) and consists of 8 hours at 100% relative humidity (condensing) at a temperature of 122 degrees F followed by 16 hours at ambient 80% relative humidity at a temperature of 75 degrees F. Matte finish sandblasted, SAE 1010 mild steel panels were used for this testing. The panels were submerged in the oils, allowed to drain for 2 hours and placed in the cabinet.
*Tests results shown here were those done within the last 24 months by an independent lab and included most major oil company GA engine oils both with and without various supplemental additives including the CamGuard formula.

Figure 1 shows the average number of days to the appearance of rust on the panels. All of the oils show a remarkable improvement with the addition of CamGuard.

Figure 1

API Derived Humidity Cabinet Testing

Corrosion testing of four oils and three additives was performed using a humidity test chamber and matte finish steel Q-panels. SAE 1010 low carbon, mild steel test panels were used for this testing. The water used was mildly acidified with hydrochloric acid. The test utilized 1 gram of 37% hydrochloric acid in 199 grams of water. The oils tested were Additized W100, 15W-50 semi-synthetic (SS), AD 20W-50, 20W-50 semi-synthetic (SS). The additive were tested as follows: Additive A 6% in Additized W100, Additive B 10% in Additized W100, CamGuard 5% in Additized W100, CamGuard 5% in AD 20W-50.

The test panels were dipped into beakers containing the test oils and additive blends. The panels were dipped at ambient temperature 75 degrees F and allowed to drain for 30 minutes. They were then suspended in an oven at 220 degrees F for 30 minutes where they continued to drain/ drip. This was done to simulate engine shutdown and helped to demonstrate a relationship between film thickness and protection.

The samples were then placed into the humidity cabinet. The temperature in the cabinet cycled between 65 degrees F and 100 degrees every 24 hours. This cycled the samples around the dew point demonstrated by condensation on the panels. The samples were checked once per day for corrosion. The crankcase of an airplane engine is an aggressive environment. Blow-by contains partially combusted and raw fuel components, combustion gasses, and water. These contaminants along with oxidized oil lead to a hostile acidic environment promoting corrosive/erosive wear that can dramatically reduce engine life. Hydrochloric acid was used to simulate the acidic/corrosive environment of the crankcase and to increase the severity of the tests. Hydrochloric acid was selected because of its use in the standardized ASTM testing protocol for certifying automotive engine oils. The Ball Rust Test (BRT) is utilized to qualify passenger car motor oils for ferrous metal corrosion protection. It exposes a polished steel sample ball, in the test oil, to a mixture of hydrochloric, hydrobromic, acetic acid, water and air. The BRT replaces the Sequence 11D engine test for rust performance in motor oil certification. The sequence IID engine test utilized leaded fuel. The results are plotted on Figure 2. The two results show the time in days to trace corrosion and to 50% corrosion (rust) coverage. The testing was terminated at 60 days for the CamGuard samples with no more than the trace rust on the panels.

Figure 2

Wear Testing

Wear testing of the four oils and three additives was performed utilizing a FALEX Tribometer at a third party analytical laboratory. The FALEX PIN and V-block is a well-known tribometer that is used for many standardized lubricant tests. These include the ASTM (American Society for testing and Materials) D-2670 Standard Test Method for Measuring Wear Properties of Fluid Lubricants and ASTM D-3233 Standard Test Method for Measurement of Extreme Pressure (EP) Properties of Fluid Lubricants. The test procedure utilized here was a derivative of the ASTM D-2670 and used by Phillips Petroleum and described in the Journal "WEAR" Volume 84, 1983. The Phillips test correlates well with camshaft wear in automotive engines using gasoline engine oils. The loads in this testing were then reduced from the above reference and specifically selected to demonstrate effectiveness of the antiwear additives in commercial aviation oils. Aircraft engines were designed before there were antiwear oil additives. The engines were designed with cam/ lifter and piston ring/ cylinder load pressures low enough that a film of heavy oil was enough to prevent excessive wear.

The test procedure consists of cleaning the test pieces and assembling them. The initial run-in procedure involved heating the test oil to 250 degrees F. Then with the pin rotating at 290 RPM the load was slowly ramped up to 150 pounds where it ran for three minutes for break-in. The load was then stepped up to 250 pounds for 1 minute and then stepped up to 350 pounds. The test was run for 3.5 hours maintaining a constant 350-pound load. After the run the PIN and V- blocks were cleaned and the total weight loss was measured and reported.

Ashless additives such as the triaryl phosphate ester functional fluids including tricresyl phosphate (TCP), butylated triphenyl phosphate (BTPP), and isopropylated triphenyl phosphate have historically been utilized as load carrying, plasticizers and flame-retardant additives in many applications. They are currently utilized extensively in turbine engine oils. These additives have never demonstrated useful performance in automotive applications i.e., the engines wear out. Automotive gasoline and diesel engines depend on the use of zinc diakyldithiophosphate zinc for antiwear protection.

Like other bench tests this is an accelerated test. The loads and initial temperatures of this test were specifically selected to test the antiwear capabilities of these oils and additives not their extreme pressure (EP) properties, which occur at significantly higher loads. It is important to remember that even non-dispersant mineral oil passes the aviation certification test and consists only of basestock and antioxidant. The ashless dispersant (AD) non-antiwear additized oils have all successfully passed certification testing and it is important to note that this is a test to compare the antiwear additive chemistries under conditions just beyond those found in an engine. The test conditions were determined by using conditions that are just severe enough that the unadditized oils failed. Only after a great deal of testing was performed under a wide variety of conditions was it determined that this procedure could be used to address the antiwear additive's effectiveness.

The temperature, 250 degrees F, was selected to minimize film thickness and help thermally activate the antiwear chemistry. Most antiwear compounds work by decomposing (activating) and reacting with the wearing surfaces forming sacrificial films. These films are worn away and replenished continuously as long as the additives last

Figure 2 shows the results of testsat the selected conditions. The samples that did not make it up to the final load, 350 pounds, are shown as failing with the appropriate explanation. The samples that made it to the final load but did not run the full length of time, 3.5 hours, are shown as failing with the appropriate explanation. The W100 failed just before it reached the 350 pound final load and was chosen to be the base case for additive testing. The 20W-50 failed at 75 seconds but at a much lower starting temperature of 150 degrees F and could have been used as the base case as well.

The additized (adt) W100 and the leading semi synthetic (15W-50 SS) both of which claim antiwear protection performed well. The 15W-50 gave a total weight loss of 54.9mg and the adt W100 gave a total weight loss of 28mg. The new 20W-50 SS, which makes antiwear claims failed 15 seconds after reaching the final load and in 5 seconds in a repeat test. CamGuard was added to both of the semi synthetics the 15W-50 SS and 20W-50 SS and demonstrated excellent results with 6.1mg and 4 mg weight loss respectively as shown in Figure two. Additive A, a well know product, in W100 demonstrated no benefit over the W100 by itself as the sample failed to reach the final load. Additive B, a polymer resin type additive in the W100 sample made it to the final load but failed after 15 seconds. CamGuard in the reference W100 sample passed with a total weight loss of only 1.5-mg.

Inclined Panel Deposit Test

Using 15W-50 Semi-synthetic oil
With and Without CamGuard

540oF - 2 hours
With CamGuard	Without CamGuard

540oF - 4 hours
With CamGuard	Without CamGuard

The Inclined Panel Deposit test is used to determine how well a lubricant resists oxidation and deposit formation due to thermal breakdown. The stainless steel panels are held at an incline at a temperature of 540 degrees F. Oil is dripped continuously along the centerline of the panel one quarter of the way down marked by the two lines. The oil flows toward the pointed end of the panel where it drips off to be collected and reapplied to the hot panel. This accelerated test is designed to emulate the deposit forming tendencies of oils.

Aircraft engines are designed to run with large clearances. The reasons for this include the age of their design, the materials used, and most importantly the fact that they are air-cooled. Large clearances between pistons and cylinders lead to large amounts of blow-by, the gas that leaks by the piston rings during the high-pressure combustion events. Blow-by gas is made up of combustion by-products such as carbon dioxide, water and lead oxides, it also contains large amounts of air, partially combusted fuel (very reactive) and raw fuel. An engine that uses 15 gallons of fuel per hour may put 0.5 gallons of partially combusted and raw fuel into the crankcase per hour. Most of these fuel components are volatile and the vapors exit the engine through the crankcase breather. Other components are less volatile and remain in the engine diluting the oil. It is the blow-by gas that contaminates the oil and gives it that characteristic smell after only a few hours. It is the blow-by components that remain in the oil that are real troublemakers. They not only dilute the oil and additives but they are extremely reactive. In the upper ring zone they overwhelm the dispersant and antioxidants leading to carbon and lead deposits. Analysis of deposits found in the upper piston ring groove show them to contain over 2% lead and therefore fuel derived. Oil companies only put enough antioxidant to protect the bulk oil from oxidizing. This however is not the problem. CamGuard uses multiple high molecular weight antioxidants to address this blow-by fuel dilution unique to aircraft engines. The result is fewer deposits, which dramatically reduces the chance of sticking piston rings or valve guide morning sickness.

We tested a popular 15W-50 semi-synthetic oil with and without the addition of 5% CamGuard. The results on both the 2 and 4 hour tests show a dramatic reduction in the total amount of deposit formed with the use of CamGuard.

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