Synthetic oils and leaded gasoline.

Not Sure

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I have heard about the disaster with Mobil 1 aviation oil and 100LL fuel that resulted in horrible lead sludge accumulation that destroyed many GA aircraft engines. This resulted in many lawsuits against Mobil and synthetic oil being pulled from the GA market and no one has dared to release another.

It has been explained that PAO oils can not hold the lead in suspension and are completely incompatible with leaded gasoline.

So my question is if your running a leaded gasoline in small engines especially something like Sunoco 110 that has many times the TEL of 100LL and run a group 4 synthetic oil is lead sludge an issue? Or was this simply caused by the aviation oils being ashless dispersant oils rather than automotive detergent oils?
 
Yes, this can be a problem with group IV oils.
100LL can solve many fuel storage issues with small engines, but when using 100LL I recommend the use of straight weight SAE 30 HD conventional oil (or SAE 20/SAE 40 depending on ambient temperature) or a lower-end group III synthetic blend if 5w30/10w30 is desired. I always used SAE 30 HD on all of the equipment I serviced at my shop. I also recommend at least seasonal oil and spark plug changes.
 
I just asked Redline this question and this was their response:

"Our products are very compatible with leaded fuels. The problem which occurred with the AV1 was that it was all PAO which had very little capacity to hold lead in suspension. Our products contain a large percentage ester which has better ability to hold lead in suspension than even petroleum products. I presume we are referring to street or track use of leaded fuels and not for use in aviation engines. Our HP oils are not designed for aviation engines."

I asked as I use 100LL in an old inboard and occasionally put sumped fuel from the bird in the old non-cat cars. As noted, Grp III and blends should be fine and yes straight 100LL leaves more deposits, etc. Another alternative, albeit more $ is 94UL.

I had just started flying during the AV1 mess and I remember seeing a Cherokee 6 engine sump that looked as if it had a thin layer of grey porch paint in it. Didn't look all that bad and IIRC the engine was open for another reason, but the shop said it wasn't normal.
 
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Sunoco 110 is listed as having roughly the same amount of lead as does 100LL. Online info says 1.5–3.0 grams/gallon for 110 (varies by batch) and a fixed 2.12 grams/gallon for 100LL.

I'm surprised a leaded racing gasoline is still available. This was news to me. Even NASCAR switched from leaded fuel nearly 20 years ago. The US EPA is supposed to have plans to replace 100LL for light aircraft with a special gasoline blend without lead, as has come up on past threads here.
 
Another alternative, albeit more $ is 94UL.
Ideally, this would be the way to go, if you can find it. It's longer shelf life and lower volatility (primary requirements of aviation fuel) should be equivalent to 100LL. 91/94/96 UL is not as yet carried by many/most airports as many/most aircraft piston engines are not certified in the US to use it, and all of the certified engines can use 100LL. None of the three airports that I use in my area have it.

The US EPA is supposed to have plans to replace 100LL for light aircraft with a special gasoline blend without lead, as has come up on past threads here.
That is what 91/94/96 UL is.

Sunoco 110 is listed as having roughly the same amount of lead as does 100LL. Online info says 1.5–3.0 grams/gallon for 110 (varies by batch) and a fixed 2.12 grams/gallon for 100LL.
Sunoco 110 Racing Fuel has 4.02 grams of lead per gallon, just under twice as much TEL as 100LL. It needs that much more TEL to achieve the 110 octane rating.
 
Can an average citizen go to a smaller regional airport and purchase these fuels? I know at the large int'l airports you have to have security clearance and stuff.

Thanks for raising this topic! Very interesting reading material.
 
Can an average citizen go to a smaller regional airport and purchase these fuels? I know at the large int'l airports you have to have security clearance and stuff.

Thanks for raising this topic! Very interesting reading material.
Depends on the airfield in question. Generally the larger the airport the less likely you will be able to or the bigger headache ot will be.

Small GA airfields especially those with grass landing strips are your best bet. These places rarely even have fences and generally let you drive right up to the pumps to fill your cans.

Larger GA airfields especially those with control towers are usually more of a pain. These places generally make you park outside the fence and carry your gas cans to the pumps you will want to bring a dolly or something to roll the gas cans back to your vehicle at some of these places as it can be a long walk. Driving to the pumps is generally a huge no no at a controlled airfield as all vehicles and aircraft are under the direct control of the towers ground controller unless you have a Air band VHF radio and the correct FCC license to transmit on it you can’t operate any vehicles inside the fence on controlled areas of the field because aren’t in contact with the towers.

Regional airports can be an even bigger pain as they might not even allow you onto the field even on foot, however if you go to the FBO they will usually fill up your cans for you especially if you give them a nice tip.

International airports are going to be the biggest pain of all. Chances are they won’t even want to be bothered for this sort of small ticket stuff. Even if they do sell you gas the prices are going to be outrageous. Had the misfortune of having to land at an international airport once due to weather and they bent me over on everything from landing fees, storage charges, and even gas that was almost twice the going rate at a GA field. International airports should be avoided unless it’s an emergency.

Be aware that some airfields even tiny ones might just refuse to let you buy gas, while others even large regional airports with airline service may be very happy to. It can’t hurt to call the FBO and ask or show up and ask it’s been my experience that most small airfields (at least around here) are very receptive to this and will gladly sell you some gas as long as you are willing to abide by their rules and regulations. If they want to to park outside the fence and carry your cans to the pumps then don’t just open the gate and drive in of you will at the very least never be allowed to purchase gas their again, and at worst might be arrested for something possibly far worse then trespassing! Driving onto a ramp or taxiway of a controlled airport without authorization is probably a serious felony maybe even considered terrorism in the post 911 world! Ask the FBO first and follow the instructions they give you and you and you won’t have any problems.


This being said I just go up to one of the local on road automotive gas stations that sell 110 leaded gas for around $9-10 a gallon at the pump of which there are several in a 30 mile radius of me including the one right down the street. It’s a lot more convenient and worth paying $2 more a gallon for rather than driving 50 miles to the local airfield, and 50 miles back to save $20 on 10 gallons of gas yet burn that much in gas or more my vehicle to make the trip negating the savings. Also I need this higher octane gas for some of my toys that are supped up and running 14-1 compression ratios or lots of boost. If I was purchasing larger quantities strictly for small engines on lawn and garden equipment it would be different. Wish I could get unleaded 93 octane ethanol free gas but the nearest station that sells it is over 250 miles away there is no other options around here. Seems to be illegal in this area to sell unleaded gasoline that is ethanol free, with the sole exception of MOGAS for aircraft use and that canned gas that costs like $30 a gallon or more. You can’t even get ethanol free at any marinas or fuel docks around here either.
 
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