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Robinson R22 & R44 Fuel Addative


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Are they talking about "Marvel Mystery Oil"? I've never used it in a helicopter, but I used put it in a Cessna 177B Cardinal to get it to stop burning engine oil. But I was putting in with the oil in the crankcase, not the fuel.


Now that I think about it, they're probably talking about Alcor TCP. I used to add that to Robinsons all the time if I was using 100LL. 100LL is not "low lead"; it's "lower lead" as compared to straight 100/130. It has FOUR times the amount of tetraethyl lead than 80/87. TCP scavages that extra lead out of the cylinder to keep it from building up on the exhaust valve and spark plugs. It comes is a one gallon can and will last you a long time.


The other thing I used to put in the oil, AVBLEND. That helps prevent exhaust valve seizures. Expensive stuff, but it seemed to work well in combination with the TCP. I only had to ream the valves at the 300-400 hr mark, then never again.


The best alternative......the AUTO GAS STC. Get yourself an autogas STC and run straight 91+ premium in the helicopter. I ran 7 R22s to TBO on straight autogas. We went through less cylinders, less spark plugs, better compression checks, etc. It will cost you about $700, but you'll save $10,000+ over the life of the helicopter in fuel cost savings. The only restriction, you cannot burn any fuel with ethynol additives (which is a problem if you're in the Midwest). And you don't need to worry about the TCP, Mystery oils, and AVBLEND anymore because there's no lead!

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Yes, it is "Marvel Mystery Oil".

Pat Cox who is a Technical Representative @ Robinson Helicopter Company sent this email after I posed him the same question:

"Mystery Oil" is Not approved and I don't know of any sanctioned test(s) confirming its performance (or lack thereof). Our best advice? Have you service people change the oil and perform Lycoming SB 388C as noted in the published maintenance schedule.



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Robinson doesn't approve ANYTHING.....that's a liability thing. I won't say his name, but there used to be a tech service rep at RHC that would tell you the "right" way of diagnosing and fixing problems. Maybe that's why he's not there anymore; but point being, if it isn't in the service manual, RHC will not recommend it.


You can use anything that is PMA'd, TSO'd, STC'd, whatever as long as it is used in accordance with the manufacturer's instructions.


Finally, I would avoid emailing RHC about that stuff....You already know what the answer will be and it's also on record. Which means Pathfinder and the warranty department will have it. Anything happens to your helicopter and they'll bring up your email--I guarantee it. Plus your really going to p/o your maintenance dept which is definately a bad thing.

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  • 3 weeks later...
  • 5 weeks later...
As noted, MMO is not "authorized" as an additive on any aircraft certificated engine. I would think extra hard on deciding to use it or not, and if you decide to use it, don't tell anybody.



i know of people that have used MMoil in aircraft engines and swear by it. (in both the fuel and added to the engine oil) Me being a mechanic/IA i can tell you that it will unstick a valve & rings in your lawnmower, but? IF ya wreck your lawnmower, you will more than likely NOT have the FAA taking fuel samples and point fingers & your insurance company wont try to weasel out of your claim ! SO? Flybull? in addition to not telling anyone?--i recomennd running out of fuel and / or oil, if you are going to have an accident/incident .

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That is very interesting about the Auto Fuel STC. How do you think that STC would work on the R22 in 98* temps at 70 plus humidity with den in 1000-3000 ft range? My A&P friends discourge Auto Fuel STC's to their fixed wing customers. They say there is icing problems and fuel system problems related to Auto Fuel STC's. I think that they are thinking the GA fixed wing pilots plane just sits in the hanger more than it flys, mentality. But, I can see in a school situation you are using the engine every day so the fuel going stale is a non event.






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The R22Bs & BIIs did just fine in super-high temps (100+) with high RH. However, the R44 did not like the 100% autogas--I had a sputter once when picking up to a hover after doing a long ground idle on blacktop. We dumped 25 gallons of 100LL in it and no problemo. We usually ran 50/50 mixes of 100LL and 93 premium in the R44.


You don't want to run it if you're going up to high altitudes or storing your aircraft for long amounts of time. We were doing at least 4-5 hrs a day on each aircraft and never had a problem.


The other thing I wouldn't do is burn autogas on a new engine. You need the lead to help lubricate the exhaust valve seats. After 100-150 hrs, they've been beaten into submission and formed a nice seal. Too much lead then becomes a problem (valve guides).


I was a seminar last weekend renewing my IA and one of the engine guys was passing around some pistons and such that had been destroyed by autogas. While a little scary, the stories behind them showed that it was the gas itself doing the harm. It was used in the wrong way.


Also, buy it from the same gas station. Before we started having it delivered, we bought it from a station in the weathly part of town where most people had fancy cars and used Premium. If you buy it from somewhere out in the sticks, who knows how long it's been down in the tank.


Also, you cannot you any fuel with Ethynol additives. This may not be a problem in your part of the country, but in the Midwest it's getting harder to find fuel without it. The used to use 10% in regular and midgrade (both had a stamp on the pump that said it.) People started swtiching to premium and the farmers had a hissy fit. They passed a bill that mandated it in all three grades and that the 10% stickers would be removed from the pump. So make sure you do an alcohol check on the fuel even if they say it doesn't have alcohol.


Also, I really can't recommend it in any other aircraft since I haven't seen its results after many hours and years. The key is experimentation--and I use that word very loosely. Get the STC and dump 5 gallons into 25 gallons of AvGas and go fly. Try it at different temps and altitudes for a while then try more.


All I know is that it ran great in our R22B, R22BIIs, & R44A, in the hot & cold climates, several hours a day. All of the cylinder & spark plug problems went away when the lead was removed from the system.


Oh, one more note, Lycoming LOVES to say, "Well, we know when you use autogas because when it comes in for overhaul we have to replace more parts." Well, with 93 being $1.00-1.50/gal cheaper than 100LL, at 10 gph, over 2200 hrs, you save $20,000-$30,000 on straight autogas......for that you can just buy a new engine PLUS those extra parts. Besides, RHC throws the cylinders and pistons away on overhauls anyway.

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