We like to think we remain instantly abreast of every important development in general aviation and now we're in possession of a scientific discovery only we can reveal to the world: If you want your phone to ring off the hook, your fax machine to choke and your e-mail inbox to overflow, publish an article comparing piston engine oils for aircraft.We did that very thing in the February 2005 issue of The Aviation Consumer and although the article was based on the most extensive oil testing we've done to date, it generated an enormous number of what we would call "yeah, but" questions. "Hey, yeah, great article on oils, but ..." wrote one reader, asking detailed and specific questions about his current favorite choices, Phillips XC and Exxon's Elite. Another reader phoned to ask which oil would be best for his twin Cessna, which is flown under 100 hours a year. Would AeroShell 15W50 be the best choice and should he add CamGuard to it?The harsh reality? We simply don't know. The more we burrow into the subject of engine oil, the more we find more heat and smoke but less light. If there's any constant truth in the aviation piston engine oil field, it seems to be that there are too many variables to make one-size-fits-all decisions about which brand or type to use. An engine that's flown daily or several times a week will probably sail right to TBO using any oil. The hard case is the occasionally flown engine hangared or tied down in a corrosive climate; it will need all the rust protection it can get and even the best oil might not save it from an early demise. Unfortunately, this scenario is closer to the typical GA engine than not.So much for our informed opinions. For this article, we've contacted the major oil companies -- Exxon, Shell and Phillips -- and presented them with the kinds of questions readers have been sending us. These extensive interviews haven't produced take-it-to-the-bank advice on any single engine oil but we think that the observations of the people who make these oils have merit and should be considered when deciding which oil to use.The aircraft piston engine oil market appears to be dominated by Shell with its AeroShell 15W50, along with various mono- or straight-grade products. Phillips and Exxon share the remainder of the market, although not necessarily equally, along with lesser players such as Chevron and BP Castrol. The latter two brands are so difficult to obtain in most parts of the country that we're not sure they're realistic choices.For this article, we spoke to Stephen Sunseri and Shlomo Antika at Exxon, Larry Norris at Phillips -- now PhillipsConoco -- and Robert Midgley, Shell's global technical director. We posed a series of questions from readers to each technical representative. Answers from Sunseri and Antika are combined in a single response.
This is a companion discussion topic for the original entry at https://www.avweb.com/ownership/answers-about-oil