Hybrid Flight C170

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ghostflyer
Posts: 1390
Joined: Mon Apr 21, 2008 3:06 am

Re: Hybrid Flight C170

Post by ghostflyer »

Most oils are designed to a specification and to a price. However a lot of oils exceed that specification and some don’t . We had Exxon oils recalled a number of years ago when it was bordering on meeting that specification and was failing engines due to a high sulphur content. It was etching out the bearings . Then was the case of shell aviation oils hardening flexible oil seals. The USA has sources within its borders that have a very good base stock in its oil which makes a better oil than what’s sourced from the Middle East or Australia. The days of synthetic made oils have levelled the playing field but still are not equal. This is very apparent with turbine oils as Mobil jet 2 was designed in the early 60,s and modern gas turbines can use it but due to running higher internal temperatures choking does occur . Even our piston engine aircraft have a choice of Straight mineral oil or a detergent based oil. Most engine manufactures require mineral oil be used for the break in of the engine and then switch over detergent oil. This is where it gets murky for me. A breaking in of a engine produces hot spots within the engine but mineral oil breaks down more readily under stress .would glazing of the bores happen more readily if engine is run in under less load ? I have heard of engines run in using detergent oil especially turbo piston engines . So the argument goes on. We haven’t even touched on additives yet?
MMO ? Now that’s throwing fuel on fire.
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eskflyer
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Joined: Sat Feb 02, 2019 1:48 pm

Re: Hybrid Flight C170

Post by eskflyer »

yep MMO , BAD STUFF. stoddard solvent and red dye and a little squirrel fat. + BAD STUFF
AA16, SHORTWING and SPAMCAN FLYER, JP
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ghostflyer
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Joined: Mon Apr 21, 2008 3:06 am

Re: Hybrid Flight C170

Post by ghostflyer »

“ squirrel fat” OMG , I love those little squirrels . No MMO for me . 8O
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GAHorn
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Re: Hybrid Flight C170

Post by GAHorn »

It’s my opinion that some understandings “transmorgrify” into misspoken details. Just to be accurate, the Exxon oil debacle was an effort by Exxon to introduce extreme-pressure additives into aviation oils. It backfired because aircraft engines are often assembled years previously using older-specification parts and older approval-basis parts such as “yellow metal” bearings etc. made of brass/copper which “leach” when phosphorus-based (not sulfur) EP additives are excessive. (Engine producers are not excited about changing parts-specifications and having to undergo/ re-do expensive approval-basis testing.)

Synthetic oils don’t escape criticism entirely either. Mobil attempted to produce an aviation oil based upon their successes in the automotive world with their Mobil 1 auto oils. It was a very expensive failure for them when it was discovered that purely synthetic Mobil oil did not scavenge lead by-products well and engine failures and premature wear was suffered by those using that product.

AeroShell also ran into troubles when attempting early development along synthetic lines and eventually produced (still) their “Semi-Synthetic” which is a blend of synthetic and mineral oils. Those are also “multi-grade” oils, meaning they have additives which alter the viscosity-behavior of the oil under varying temperatures. (Think of it simplistically like this: A 20W50 grade will behave similar to SAE20 oil at cold temps and SAE50 at higher temps.). The drawback to multi-grade oils is that they often find ways to leak more than heavier viscosity oils. (Often believed to result from the lower viscosity behavior to find a way thru smaller places like loose gaskets, etc. I personally ran an unscientific experiment with the O-470 powered Baron I used to own by running AeroShell 15W50 in the right engine and straight 100W (SAE50) in the left and found that the right engine consumed oil at a much higher rate than the left. Switching oils in reverse, the multi-grade remained higher consumption even on the left engine. It’s why I became a firm follower of straight-wt aviation oil, but that’s a privilege I can enjoy down here in Texas. If I lived up NAWTH and had frequent cold-starts without pre-heat I’d certainly use multi-grade.)

The term “mineral oil” has been mis-applied (yours-truly included) as that term originally meant oil from “mineral sources” meaning a drilled oil well (as opposed to synthetic, vegetable or animal derivations. Castor oil was a favored oil in early aviation.) In common parlance when applied to aviation oils it usually refers to Non-Additive engine oil, as opposed to “Ashless Dispersant” (not detergent) oils.
(Automotive oils are usually detergent types designed to “clean” engines, but detergents often leave hot, glowing particles in the cylinder which might lead to pre-ignition/detonation, especially at altitude, in aircraft engines. Aviation oils which have scavenging additives that do not leave those deposits are often confused with automotive detergent oils and so the mis-nomer occurs. Ashless-Dispersant aviation oils keep combustion by-products and dirt in suspension so that those contaminants drain away with the used oil at oil change periods.
It was the “old-timers” advice (to which I still subscribe) that an engine run for a long time on mineral oil (non-additive) should not be switched to dispersant oil because the dispersants might release the sediments accumulated in the sump and send it circulating where the dirt can cause damage. I believe that is a genuine risk, and also why I advise against the practice of using “cleaners” and other snake-oils that aren’t approved for aviation. It’s my opinion that once sediments have attached themselves to the bottom of a sump then it’s unwise to move it again until overhaul cleaning-inspection.

(PS: It’s my thought that MMO may contain phosphorus additives. When phosphorus was discovered to have extreme-pressure characteristics it became a hot-item in the automotive world. Some radial engine operators swear by it for keeping valves and spark plugs clear of lead deposits. Tri-Cresyl-phosphate is the active ingredient in Alcor TCP and similar fuel additives. I don’t have a problem with phosphorus-based additives in fuel because it doesn’t live-in/circulate down in the lower engine where bearing issues may exist. The problem which exists using it in aircraft besides the legal one of no-approval-basis is... it’s carrier is likely kerosene. Kerosene, diesel, and jet fuel is not something most people would deliberately put into his gasoline-powered airplane.

That’s my unsolicited blabber. Use it at your own risk.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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ghostflyer
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Re: Hybrid Flight C170

Post by ghostflyer »

Very well put George , that issue about swapping from long term use of straight oil over to multi weight oils is very true. I do not know how many people have ruined their engines through this practice . It’s made me heaps over the years .It was many years ago Mobil came out with a add that made many claims about this “NEW” multi weight oils and people just changed over from mineral oil [single weight] There were even aviation shops that started using this new oil.
Back in the early eighties I had the privilege of operating a PBY-Catalina flying boat. It was retro fitted with 2 cyclone wright 2000 engines up rated to 2200. But when it was cold we used to put av-gas in the oil tank to dilute the thick oil [tar] . After about 1 hour and oil at normal temperature the fuel would be boiled off . It was fun those days having black arms up to the arm pit working on those cyclones .[8hrs to do a plug change ]
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