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100LL, lead, Decalin and oil filters

NinerBikes

Well Known Member
Helped my buddy Bob do his conditional inspection this year in March, where we were at about 220 Hrs Hobbs.

Bob runs a LOT of 100LL with Decalin at 1/2 oz per 10 gallons.


While doing the oil change, I cleaned out the oil sump tank, disassembled it, and cleaned /wiped out all the lead accumulation at the bottom of the tank.

It kind of got me thinking about where all that lead ends up. Is there lead accumulating at the bottom of the crank case too? Bottom of the gear box?

What about what it does to the oil filter? Is there lead build up in the bottom of the oil filter too? Does the lead stay in suspension or fall out, or end up clogging the filter medium?

Shell sport Plus 4 oil 10w-40 being used.

Sorry, too much coffee this morning has me thinking "what if".
 
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Lead is heavy. My guess is if you are finding lead sludge in bottom of oil tank it is probably also being slung by crankshaft, gears in gearbox, and other high speed rotating elements within the engine. I've never seen the inside of 912 running 100LL but I have rebuilt continental A65-8 where lead is caked to inside surface of crankcase. Even though 100LL is advertised as low lead it is still high tetraethyllead (TEL) for anti-knock. Aircraft engines are very lightly built and cannot withstand pre-ignition (knock) without self-destructing. High amount of TEL in the fuel and a very conservative spark advance is standard practice for aircraft.
 
Same here, Costco Tier 1, but it's 91 unleaded Mogas in Los Angeles.

I went in to Pep Boys today to get some Mobil 1 4T 10w-40 and I'd looked it up on line. They are having a 20% off instant discount, so I had to order a 6 pack of it at $9.19 instead of 11.49 per qt. I will run Mogas ONLY with this motor oil.


Guess I got lucky on that one, the Rotax filters are about $20 a whack.

They do use a special high pressure full oil flow release valve on them, unlike the other versions for cars, made by Mann -Hummel filters. It's that 5500 rpm continuous and 5800 for 5 minutes that really ups the oil pressure requirements while not bleeding off unfiltered oil into the engine components that makes the oil filter unique.
 
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I went in to Pep Boys today to get some Mobil 1 4T 10w-40...

NinerBikes,

Your first post mentions your friend uses a lot of 100LL. I thought you weren?t supposed to use fully synthetic oil with 100LL because it won?t hold the lead in suspension. Isn?t Mobil 1 4T 10w-40 fully synthetic? On their website, Lockwood says, ?Synthetic oil does not do a good job of suspending the lead and getting it from the engine to the oil tank.?
 
NinerBikes,

Your first post mentions your friend uses a lot of 100LL. I thought you weren?t supposed to use fully synthetic oil with 100LL because it won?t hold the lead in suspension.

That is correct.
That is why Aeroshell Sport Plus 4 is a semisynthetic oil.
 
Unleaded Mogas and 100% synthetic oil work great together. Mogas can have ethanol which is preferred by Rotax. Any oil used in 9-series Rotax where engine crankcase and gearbox share same lube must be formulated special for power transmission gear drives. Mobil 1 Racing 4T 10W-40 is formulated for motorcycles that have transmission and lower-end of engine all in one case sharing same oil.
 
NinerBikes,

Your first post mentions your friend uses a lot of 100LL. I thought you weren’t supposed to use fully synthetic oil with 100LL because it won’t hold the lead in suspension. Isn’t Mobil 1 4T 10w-40 fully synthetic? On their website, Lockwood says, “Synthetic oil does not do a good job of suspending the lead and getting it from the engine to the oil tank.”

My friend runs the AEROShell Sport Plus 4 10w- 40 semi synthetic, I know, I bought him 2 filters and 7 liters of it for his birthday last Sept. He changes oil every 40 hours on the Hobbs, since running 100LL. I don't know how many hours of running 100LL and it's lead will stay in suspension in the Sport Plus 4 oil, between oil changes with Decalin run as additive.

The plane I bought is back east, has 11 hours on the oil and filter, AEROShell Sport Plus 4. I will have it ferried to CA, pilot will run 100 LL and Decalin to get it back home. Once home, I'll run the last of the 100 LL through it, fill up with Mogas, run 2 or 3 hours of that through it, then it's Mogas and full synthetic diet, as exclusively as I can make it.

I will not be making exceptions for 100LL, unless the Shell oil is installed first.
 
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The plane I bought is back east, has 11 hours on the oil and filter, Shell Sport Plus 4. I will have it ferried to CA, pilot will run 100 LL and Decalin to get it back home. Once home, I'll run the last of the 100 LL through it, fill up with Mogas, run 2 or 3 hours of that through it, then it's Mogas and full synthetic diet, as exclusively as I can make it. I will not be making exceptions for 100LL, unless the Shell oil is installed first.

Congratulations on your new plane! It's good to have another -12 in Southern California! Post photos when you get a chance.
 
Cross country flight

Those that are using 100% synthetic, how do you deal with a 1,000 mile cross county flight. It's not like mogas is available at most airports? Not judging your ways but if there is a secret I want to know about how to deal with a long cross country and finding or getting mogas.
 
Congratulations on your new plane! It's good to have another -12 in Southern California! Post photos when you get a chance.

Will do... it will be an adventure, learning to fly in your own plane. People say a RV-12 is easy to fly... i'm hoping it's easy to learn how to land.

So much to learn.

2012, AP, also has steam gauges, airspeed and altimeter and backup dynon D1 attitude as well as back up Garmin Aera 500, wheel pants, 168 hours on Hobbs, Aux 6 gallon fuel tank and pump behind PIC. Will need to update to Dynon Skyview Touch, soon, it's in the budget.

Picture it in Navy Blue, and a silver pin stripe. Made me an offer I couldn't refuse, as all service bulletin updates with doublers and triplers, have been performed, not just "inspected" front landing gear parts coming my way, already on order, and trim motor bushing too.
 
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Those that are using 100% synthetic, how do you deal with a 1,000 mile cross county flight. It's not like mogas is available at most airports? Not judging your ways but if there is a secret I want to know about how to deal with a long cross country and finding or getting mogas.

I'd suggest an oil change to Shell Aeroshell, Sport Plus 4 semi synthetic before the trip, and run Decalin Run Up at a ratio of at least 1/2 oz or more per 10 gallons of fuel per fill up of 100LL. Some go 50 hours on Hobbs before oil changes, I'd tend to go closer to 35 or 40.

One option for lead free Mogas http://flyunleaded.com/mapusairports.html

Another option, though early in the season. Go to "Layers tab"," FBO" then select "Mogas' for fuel.

https://skyvector.com/
 
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I believe you can run up to 30 percent 100LL and be OK with full Synthetic oil. When I bought my RV-12 the previous owner ran Mobil Synthetic in it and I flew it home 1700 miles and of course had to burn 100LL. When I changed the oil it was dark but overall there was less than 30 percent 100LL burned since the last oil change. Ill burn non ethanol Mogas from here on out unless I fly far away again.
 
I believe you can run up to 30 percent 100LL and be OK with full Synthetic oil. When I bought my RV-12 the previous owner ran Mobil Synthetic in it and I flew it home 1700 miles and of course had to burn 100LL. When I changed the oil it was dark but overall there was less than 30 percent 100LL burned since the last oil change. Ill burn non ethanol Mogas from here on out unless I fly far away again.

Curious, heading west, how many hours on the Hobbs meter to get it 1700 miles for the trip home? Month of year and headwinds? Whereabouts did you go over the Continental Divide?
 
I believe you can run up to 30 percent 100LL and be OK with full Synthetic oil. When I bought my RV-12 the previous owner ran Mobil Synthetic in it and I flew it home 1700 miles and of course had to burn 100LL. When I changed the oil it was dark but overall there was less than 30 percent 100LL burned since the last oil change. Ill burn non ethanol Mogas from here on out unless I fly far away again.

Back before Rotax switched from publishing a list of approved oils to just recommending Aeroshell Sport Plus4 (Mobil 1 Racing 4T was on the approved list at that time) they stated that any of the fully Synthetic approved oils were for use with unleaded fuel only.

If you were using a semi-synthetic, you were allowed to use leaded fuel.

If you used leaded fuel more than 30% of the time (with semi-synthetic oil) , then you were supposed to reduce oil change interval times by 50%.
 
Congratulations on your new plane! It's good to have another -12 in Southern California! Post photos when you get a chance.

Kind of felt a little lucky to not buy one in red, and white. Wish it was raw in finish and 25 #'s lighter, but buying used, you get what you get.



 
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Looks good! Are you going to ride along on the ferry flight?

Unlikely, too difficult to find and coordinate.

I'd probably need a light weight female CFI to instruct to make under gross 1320# with a little bit of carry on. Finding one of those that wants to be cooped up with a stranger for 20 + hours of flight into headwind going west is looking for a needle in a haystack.

As it is now, I have a 165 # guy that's looking for an adventure, with friends along the way he wants to visit. He's in some sort of mystical "Quiet Birdmen" secret society, or something like that. You have to be voted in, so I am assuming he's done something right with all of his flying. Frankly, to me, it sounds sort of like some E Clampus Vitus group of airmen.

Plane does have an additional 6.5 gal nominal aux fuel tank, so 26.3 gallons will make for easy 450 nautical miles between either inexpensive 100LL fuel stops, or unleaded Mogas fuel stops, if at all possible. Current owner runs 20% 100LL with ethanol free 90 mogas, and says octane rating is fine with the motor. No lead micro ball build up on spark plugs.

I bought 12 gallons of 91 at the local Costco yesterday here in CA, $ 2.799 a gallon, and going up in price. Took a sample of it and tested for ethanol. Trace amount, at most 1% to maybe 1.5%. Fuel stunk like he77, not at all like 100LL we get around here, it really bloats my Jerry cans with the vapor pressure.
 
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COVID flight planning might include a gallon of hand sanitizer and disinfectant wipes. Maybe add'l 12#...
 
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