Question About Running 50/50 Blend of Aeroshell and Synthetic

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Pilot101

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Pilot101
I am considering running a 50/50 blend of Aeroshell 100W conventional oil and 15W-50 synthetic in an experimental turbocharged Lycoming IO-540.

Yes I heard that pure synthetic was tried in 100 LL AVGAS engines and there was problems because the synthetic oil did not have detergent properties and it was not washing away the lead contaminants so running 100 percent synthetic is most likely not good.

That is disappointing because the lubrication properties and warm oil viscosity of synthetic oil is superior to the conventional mineral oil...so what does the collective think about a 50/50 blend???

Would it not be able to achieve the best of both products meaning the cleaning properties of the dispersant aviation oil and the better lubrication of the synthetic?

Has there been any studies on this thought with respect to AVGAS 100 LL engines?

Any thoughts would be greatly appreciated!!!
 
https://www.shell.com/business-customers/aviation/aeroshell/piston-engine-oil/w15w50.html
As you can see, 15w50 is already a blend, and had been formulated for aviation engines, which includes chemicals to help get rid of the lead. I wouldn't start experimenting in my engine, but that's just my opinion. Some probably do.

Lot's of reading here if you do some searches...and if you want more heady goodness than you probably care about, check out the Mike Busch videos on youtube.
 
Personally, I think you’re trying to solve a problem that isn’t there...

Even though the oil can be safely mixed, I wouldn’t do it because you really don’t know what you’ll end up with unless you send it to a lab. If you’re going to go to that much work, why not just have oil blended to whatever specs you want?

If it’s experimental, why not look at oils intended for other applications?
 
Because I am based in a northern Rockies climate a large number of the airplanes here run multigrade oil year-round, including me in the pair of IO-540s on the Aztec and my O-360 powered Husky.

I don't know one owner here that blends anything in with AeroShell 15-50, most have been running it for years, and they don't seem to have any issues. I used to run only AeroShell multigrade for many years, but switched a couple of years ago to Phillips 20-50 only because the premium to buy AeroShell has become excessive in my view.

I agree with the earlier comment that you are trying to solve a problem that doesn't exist if you are planning to use AeroShell multigrade. It's an ashless dispersant oil.
 
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Shell says you can mix any oil that is approved for your engine with any other and it will be fine.
 
flyingron said:
Shell says you can mix any oil that is approved for your engine with any other and it will be fine.
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Mixing wasn't the issue. The rationale presented by the OP doesn't support the need to have to do so.
 
Pilot101 said:
I am considering running a 50/50 blend of Aeroshell 100W conventional oil and 15W-50 synthetic in an experimental turbocharged Lycoming IO-540.

Yes I heard that pure synthetic was tried in 100 LL AVGAS engines and there was problems because the synthetic oil did not have detergent properties and it was not washing away the lead contaminants so running 100 percent synthetic is most likely not good.

That is disappointing because the lubrication properties and warm oil viscosity of synthetic oil is superior to the conventional mineral oil...so what does the collective think about a 50/50 blend???

Would it not be able to achieve the best of both products meaning the cleaning properties of the dispersant aviation oil and the better lubrication of the synthetic?

Has there been any studies on this thought with respect to AVGAS 100 LL engines?

Any thoughts would be greatly appreciated!!!
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As others have noted, Aeroshell 15W-50 is semi-synthetic, not synthetic. It has been on the market for quite some time and has not exhibited the problems that the full synthetics did that caused them to be withdrawn from the market. That said I prefer Phillips 20W-50 which, while multi-viscosity, is non-synthetic.
 
Seems like a potentially very expensive experiment.
 
Pilot101 said:
I heard that pure synthetic was tried in 100 LL AVGAS engines and there was problems because the synthetic oil did not have detergent properties and it was not washing away the lead contaminants
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That's a little garbled. The Mobil 1 synthetic that failed in aircraft engines did have detergents; but the problem was that lead salts are not soluable in the synthetic oil chosen (poly alpha olefin), *and* Mobil recommended long change intervals, like 200 hours. So the interior of the engines became a lead sludge disaster area.

Your proposed 100/15-50 blend doesn't make any sense... 15-50 aviation oil is already a synthetic/mineral oil blend...

What performance attribute of, say, Phillips 20-50 does NOT meet your criteria? The only rationalization I'm aware of to run 15-50 is at very low OAT, where mineral oils can congeal in the oil cooler.

Keep in mind, AeroShell 15W50 contains triphenylphosphate, which isn't always a good thing, unless you have an O320H2AD engine where it's required by AD.

Let us know what problem you're trying to solve.
 
https://www.aviationpros.com/home/a...ifferent-brand-weight-or-type-harm-the-engine

"I'm not recommending that owner/operators make their own oil by mixing a quart of one type of oil with a quart of another type oil during oil changes, but rather when a situation arises where you are down on oil, the decision to add a different brand or grade is a good one since this will not cause any engine problems." --Phillips 66 aviation oil product technical manager
 
PaulMillner said:
That's a little garbled. The Mobil 1 synthetic that failed in aircraft engines did have detergents; but the problem was that lead salts are not soluable in the synthetic oil chosen (poly alpha olefin), *and* Mobil recommended long change intervals, like 200 hours. So the interior of the engines became a lead sludge disaster area.

Your proposed 100/15-50 blend doesn't make any sense... 15-50 aviation oil is already a synthetic/mineral oil blend...

What performance attribute of, say, Phillips 20-50 does NOT meet your criteria? The only rationalization I'm aware of to run 15-50 is at very low OAT, where mineral oils can congeal in the oil cooler.

Keep in mind, AeroShell 15W50 contains triphenylphosphate, which isn't always a good thing, unless you have an O320H2AD engine where it's required by AD.

Let us know what problem you're trying to solve.
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What is the downside of triphenylphosphate?
 
luvflyin said:
What is the downside of triphenylphosphate?
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Nothing proven or concrete, other than internet anecdotes. Look at SDSs for health, safety, or environmental info. Other than that, it devolves in a “this oil is better than that oil because...”, with no data and nth-hand information.
 
455 Bravo Uniform said:
Nothing proven or concrete, other than internet anecdotes. Look at SDSs for health, safety, or environmental info. Other than that, it devolves in a “this oil is better than that oil because...”, with no data and nth-hand information.
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So you don’t believe the assertions when it comes from chemists familiar with the subject? That’s where that information originated from...

That said, I think people obsess about oil far too much. I’ve been deeply involved with engines and mechanical things my whole life and can’t ever recall seeing a failure that could be directly attributed to using one oil over another, when an oil called for by the manufacturer was used. Use whatever brand you feel best about.
 
mondtster said:
So you don’t believe the assertions when it comes from chemists familiar with the subject? That’s where that information originated from...

That said, I think people obsess about oil far too much. I’ve been deeply involved with engines and mechanical things my whole life and can’t ever recall seeing a failure that could be directly attributed to using one oil over another, when an oil called for by the manufacturer was used. Use whatever brand you feel best about.
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You and I agree.

I’ve been in the chemical industry 30 years. I believe in data. If I or you or anyone else on POA had direct access to someone who worked in a lab on testing and in follow-up field tests with a valid statistics, I’d believe them. Otherwise, the usual “I know of”, or “I heard”, or even “I’ve seen 3 engines running X brand oil not make it to TBO” without a formal causal analysis makes me a skeptic (use the current virus as an example of what and who to believe...whatever your beliefs are, doesn’t matter).
 
luvflyin said:
What is the downside of triphenylphosphate?
Click to expand...
A brief synopsis: Lycoming introduced the O320H2AD engine, using automotive-style tappets. Engines not used everyday developed tappet spalling issues, due to very high cam lobe contact forces. Lycoming came up with a mod for the engines, *and* mandated by AD addition of triCRESYLphosphate (TCP) to the oil. The phosphate creates a anti-scuff layer on the tappet.

Then... due to toxicity concern, oil blenders began instead adding triPHENYLphosphate (TPP), which is less toxic than triCRESYLphosphate. It works as well as an anti-scuff... however, TPP disassociates at lower temperatures into phosphoric acid. With combustion byproduct water in the oil, this was attacking seals and copper in the oil circuit, like oil coolers. Those on oil analysis saw copper levels rise by a factor of 10 to 100, which was concerning. (See Blackstone report on trends in oil analysis.)
Shell responded by adding a copper corrosion inhibitor to their TPP oils: W100+ and 15W50. This reduced the excess copper corrosion (but didn't eliminate it). It didn't do anything to counter leaking seals. See Shells update on their improved 15W50.

If you're not running an O320H2AD engine (or one of the small handful of other similar Lycomings... see the AD) then having TPP in the oil accelerates corrosion and seal deterioration. Phillips has recently come out with a 20W50 "Victory" oil that also has TPP, and is similarly disadvantageous for other than the AD-covered engines.

And so... unless the AD requires it, my advice is to use oils without TPP.
The best general solution, as I see it, is Phillips 20W50 (*not* the Victory oil) plus Camguard. Camguard also includes a seal rejuvenation agent, so even if your pushrod seals, for example, are leaking now, Camguard should prevent further deterioration, and may even cause the leaks to stop.
 
455 Bravo Uniform said:
Nothing proven or concrete, other than internet anecdotes.
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May I suggest you review Blackstone's report on oil analysis trends, and Shell's announcement on the reformulation of 15W50? Or, you could look at Camguard's website, where they detail the driving factors for adoption of Camguard instead (recognizing that they have a dog in the fight).
 
455 Bravo Uniform said:
If I or you or anyone else on POA had direct access to someone who worked in a lab on testing and in follow-up field tests with a valid statistics, I’d believe them.
Click to expand...
You may wish to start with Blackstone's report... take a look also at Aviation Consumer's lab test of the various oils and additives, focusing on corrosion protection.
 
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