the zinc oxide ash will then plate to the engine head and exhaust valve, causing detonation, since it will not transfer heat as readily as the head itself. Automotive oils use sodium alkylbenzene sulfonate as a detergent additive, and zinc dithiophosphate as an extreme pressure (anti-scuffing) additive. The reason you do not use automotive oil in aircraft is that the additives in automotive oil are not good for aircraft.

first time i have put it up here, hopefully molekule will check it for errors. If Mobil had only done a bit more research.īelow is my standard, canned reply to this subject that comes up in the grumman gang at least once a year.

Jay - Aviation oils are 'Ashless Dispersant' types, with minimal additive packs (although third parties are starting to market them like AvBlend - which is junk but has 'FAA Approval', and ASL CamGuard - which is going through the FAA process and has some Calcium and Zinc compounds I believe.) This is not about fouling plugs (100LL AvGas doesn't need any help!!!) but more about deposit buildup in the valvetrain, which I what I believe doomed AvMobil 1. This took over 6 months, for a component that already had PMA and TC for my motor!!! That minor difference actually require flight testing, an inspection by an FAA Designated Engineering Rep (DER), AND an approved Flight Manual Supplement. I installed a new engine monitor that had already been approved for my engine (O-360-A4K), but not my airframe (AA-5B). When you install the 'new' part, you need to file an FAA Form 337 with the Flight Standards District Office (FSDO). If it is a part that was not in the original design for certification, then you also need a Supplemental Type Certificate (STC). Just about every part must have a Parts Manufacturing Authority (PMA) approval (like the old MIL-SPEC.) Not every manufacturer, almost every part number. The lawsuit costs just add on to the mix. The cost to test and certify a new design piston engine for aviation is very high, and not due to lawsuits, but to 14 CFR requirements. Lab Comments: 'Wear read perfectly at about half average', 'all metals in proper balance for engine type', 'blow-by characteristics appear normal'.įowVay - it is actually a combination of factors. Moly, Nickel, Manganese, Silver, Titanium, Potassium & boron, all 0 actual & 0 average. There were approx 45 hours in between where we didn't get a sample (over zealous apprentice mechanic drained oil before I showed up w/ the bottle ). Prior sample is from last year w/ approx. Piper Dakota, Lycoming 0540 (horizontally opposed, air cooled, 540ci, 6 cyl, 235hp), approx 1,600 hrs on the engine (2,000TBO), 20 hrs on the oil and 3 quarts added. oil sample back so here's one if you are interested: There aren't too many aircraft UOA's here and I just got the bird's regular 6 mos.

Lycoming 0540 mm