Plane & Pilot
Tuesday, May 7, 2013

There’s More To Oil Than You Think!

Taking care of your engine with aviation lubricants

Phillips 66
To get rid of water, you need to run the engine, and not just at idle power. An oil temperature of at least 180° F is required to drive water out of the engine. Getting the engine that hot will require flying it, at least for a couple of touch-and-goes. Visser also warns that many analog oil temperature gauges are poorly calibrated—just getting the needle into the green may not be enough. He recommends having a mechanic calibrate the temperature bulb and add a paint mark to show exactly where 180 degrees is on the gauge (those of us with digital oil temperature indicators, on the other hand, don't need to do this). If you can't get the oil temperature that high, check with your mechanic to see if a winterization kit is available, which will block some airflow to the engine.

If you won't be flying an airplane at all for an extended period, consider switching to a preservative oil, such as Phillips 66 Aviation Anti-Rust 20W-50 or AeroShell Fluid 2F. They're both fly-away oils that don't have to be drained out before the airplane is flown, but you'll want to replace them with regular AD oil after no more than 10 hours of operation. For airplanes flown infrequently (once or twice per month) in high-humidity areas, Phillips recommends mixing up to 10% Anti-Rust 20W-50 with a conventional AD oil (such as Phillips 66 X/C 20W-50) to get a combination of corrosion protection and AD oil performance. On the other hand, ExxonMobil, which doesn't offer a dedicated preservative oil for aviation use, builds a rust inhibitor into their ExxonElite 20W-50: "Moisture may still diffuse through both the oil layer and the rust inhibitor layer, but it will take longer because of the water-repelling nature of the additive, which offers you greater protection against rust." Jerry Toenjes, an AeroShell sales team leader, pointed out that his company's W80 Plus, W100 Plus and 15W50 oils "include Lycoming L-16702 anti-corrosion additive in the proper concentration" that "helps to protect your engine in sporadic, limited use."

Some engines need additional additives. Lycoming's O-320-H requires a phosphorus-based "anti-cuffing" agent that reduces cam wear. It's available alone (Lycoming LW-16702) and is also blended into oils from several major vendors. According to Visser, it may reduce wear on infrequently flown engines.

Other Engines
Now that we've covered the ins and outs of conventional piston-engine oils, what if you're flying an ultralight, light-sport, or diesel engine airplane? The same basic rule applies: Check the owner's manual. It will recommend an appropriate oil for your engine. AeroShell offers oils for two-cycle and four-cycle engines used in ultralight and light-sport aircraft and a fully synthetic diesel oil for use in engines such as the SMA diesel Cessna now offers as an option in new Skylanes. Toenjes told me those oils use different technology and shouldn't be mixed with conventional mineral-based aviation oils. He added that AeroShell is using a fully synthetic technology in its diesel oil because lead isn't an issue for those engines.

One more thing to consider is oil analysis, in which a sample is collected during an oil change and shipped to a lab for evaluation. Phillips 66 Lubrication Engineer Steven Strollo told us: "Oil analysis accompanied by engine oil filter examination for any engine regardless of drain interval is suggested to detect and correct operating problems, recognize poor maintenance or repair practices, identify excessive operating conditions and increase engine life." ExxonMobil goes further: "Send a sample of your oil to a qualified laboratory every 60 days whether you've flown much or not, and ask them to test it for water content. If the lab says you have water in your oil, you may need to raise your sump temperature or change your oil more frequently."

Labels: Pilot GearGear

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