Between last year’s record-high fuel prices and this year’s rock-bottom economy, it’s no surprise to anyone that General Aviation flying is way, way down. That’s bad news for our industry as a whole and really bad news for the long-term health of the tens of thousands of piston engines that lie idle for weeks at a time.
While the impact of this problem would probably have gone unnoticed to most of us, luckily it didn’t slip past the folks at ConocoPhillips. "It’s just amazing how many pilots are lucky to get 30 hours of flying a year," explained Harold Tucker, Director, Technical Information and Training, Commercial Lubricants for ConocoPhillips Company. "It’s a shame. Sitting without use is much harder on the equipment than using it and maintaining it regularly."
So what’s an owner to do if they fly less than 10 hours a month? Switch to an antirust oil for the corrosion protection, or stay with a multigrade and hope for the best? "We get asked the question all the time by pilots at airshows," Tucker said. "If you have 100 percent antirust, you also have 100 percent mineral oil with no ashless dispersant or cleaning additives. We would be a lot more comfortable if they used a percentage of the antirust oil with their regular oil."
Phillips’ 10 Percent Solution
But how much antirust oil is just right? Tucker said that before they could recommend a blending of their Aviation Antirust Oil 20W-50 and their X/C Multigrade Oils, they first had to conduct some tests to find out the best ratio. They started by using the testing criteria spelled out in the SAE J1899 guidelines. "We ran all the tests by putting different percentages—up to 10 percent of the antirust oil," Tucker said. "We didn’t run the 150-hour or flight tests because it was already an approved and proven product."
"It may comfort some people to know we’ve had this product [Antirust Oil] and it’s been used by aircraft OEMs for over 30 years," he added. "They use it as a fly-away oil. It’s an all-mineral product with a heavy dose of antirust in it. It’s pretty potent when using it 100 percent."
Through all its testing, the Antirust/Multigrade mix delivered excellent results. "We wanted to leave enough ashless dispersant in the product to assure the cleanliness of the engine so people who don’t fly their airplanes very often can add up to 10 percent of the Antirust Oil and get really good rust protection and still have the cleanliness of an ashless dispersant oil," Tucker explained.
8 Quarts Divided by 10 Percent Equals…
"I wish there were a simple solution as far as the 10 percent guideline, but there are such a variety of engine types," he added. "You have a Cub Cadet out there with a four-quart crankcase and the bigger 470s and 540s with 10- and 12-quart crankcases. Then you have the radials that hold gallons in their oil tanks. We figure pilots can come to grips with a 10 percent mixture."
While the company recommends replacing the regular oil with a maximum of 10 percent of the Antirust Oil, Tucker said that if it’s easier, then that percentage can swing down to five percent by volume and you’ll still get much better corrosion protection. "A little less than the 10 percent gives you a really good boost. Even five percent would be a significant boost in rust protection."
That’s good news, considering that the 10 percent is going to be depleted as you add the regular multigrade oil between oil changes. "That percentage will probably be down significantly by the time you get to the next oil drain interval," Tucker said. "We don’t think it’s necessary to try and top off with additional antirust and try to keep the 10 percent ratio. Even if you’re down to two or three percent after four months, you’re still getting significant rust protection compared to doing nothing at all." The fact that you’re flying enough hours to top off the crankcase with fresh oil between oil changes is evidence that you’re using the plane enough that you don’t need the additional rust protection.
And speaking of those oil change intervals, Tucker stressed that even though you’ve taken great strides to protect the insides of your engine from rust and corrosion, you still need to stick to the same oil change intervals recommended by the engine OEM. "You need to change the oil every four months no matter what," he said. "You also need to run the engine for a while after you change the oil. You need to get that fresh oil and antirust oil dispersed in the engine bearings and oil passages. Ideally, you should fly it for an hour or so—but running it for a while to get the oil circulated is better than nothing."
Now that ConocoPhillips has developed a system to help improve the engine’s well-being during long periods of inactivity, maybe someone will develop a "solution" to keep an infrequent pilot’s skills from getting rusty.
For more information, visit
http://www.phillips66aviation.com.
Dale Smith has been in love with airplanes and flying forever. A prolific aviation journalist, along with this magazine, Dale writes for numerous other aviation magazines. When he’s not writing fun stuff about airplanes, Dale is also a principle partner in Flying Boat Creative Services, an advertising agency specializing in aviation. Send questions or comments to editor@piperflyer.org.
