Posted: Mon Apr 02, 2007 5:13 pm
I'm just repeating what the TCM VP-Technology and several TCM tech reps told me while I was at the Mobile plant. Apparently running the engine burnishes lifter faces, which makes them more rust resistant. In fact, TCM coats lifter faces with phosphate during the manufacturing process (actually, the subcontractor does) to prevent lifter face rusting until they are installed and "run-in."Why would the first hours be more likely to contribute to rust than any other time in an engine's lifetime?
(And if rust were the concern in an un-preserved engine which did not receive regular operations, then I'd recommend a single-grade oil and to stay away from the "plus" oils which might have phosphates.)
Similarly, cylinder walls are quite rust prone if stored before being broken-in. Beech had a problem a few years ago with this in a number of Bonanzas that were stored before being sold.
Every reputable source, from Aviation Consumer on down, recommends the anticorrosion and antiwear oils if an engine isn't regularly used. If the airplane is being flown regularly, use whatever color can suits your fancy--they will all get the job done, so long as it's AD oil.
There was supposedly a problem with bearing erosion from using Aeroshell 15W-50. Aeroshell changed the formulation quite a few years ago to take out the compound that was implicated, and there have been no subsequent issues. Similarly, some A&P's argue that switching to a multigrade oil from straight-weight will cause an engine to start leaking. There's no science to support this that I know of. I switched from straight weight oil to multigrade in an IO-550, and a slight pushrod seal seep went away after the change. Just another anecdotal experience than signifies nothing.
