Honest question about aviation oil

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I've been trying to learn a little bit about aviation oil, and here's what I've come up with. Aviation piston engine oil contains no metal based additives, and there are both ashless dispersant and non dispersant oils. Most available are mineral, with exception to oils like aeroshell 15w50.

Ok. So if any of that is incorrect please dont hesitate to correct me, because that's about all I can find.

Here is my question; why dont vintage auto enthusiast use aviation oil instead of "classic car oil". Why dont we use aviation oil in compressor pumps in hot climates? It seems to me that aviation oil is low or no detergent, much like classic car oil and compressor oil, and it seems it cools almost better than in lubricates. Moreover, the aviation oil isn't any more expensive that classic car oil and there are plenty of online vendors for it, plus most small airports sell it. Given that the zinc issue doesn't really apply to most classic cars with standard camshafts, why isn't this a thing? These guys usually change the oil pretty often anyway, so what's the disadvantage?
 
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Mainly because no auto fuels contain lead. Piston aircraft oil still has to deal with lead deposits.

Let me rephrase that. No auto fuels that are commonly used on the highway contain lead. I'm aware there are race fuels and specialty fuels that do.

I wonder the opposite. When they finally get around to going no-lead in piston aircraft, will their oils slowly move more towards the auto end of the spectrum?
 
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Strictly hearsay, and I don't even remember who, but many years ago someone at an airport told me the aircraft oil was designed to burn clean so it will not foul the sparkplugs, even though most of those engines have two sparkplugs per cylinder.

Maybe someone here on BITOG who knows more about this can verify this requirement.
 

Red91

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With respect, why would automotive gas being lead free have anything to do with not using aviation oil in a car engine? That too is a serious question. I really dont know. The metal based detergents and anti wear additives of auto oil caused pre detonation and severe piston damage when burned in an airplane engine, but what negative effect would be seen if an old car burns a little aviation oil?
 
Strictly hearsay, and I don't even remember who, but many years ago someone at an airport told me the aircraft oil was designed to burn clean so it will not foul the sparkplugs, even though most of those engines have two sparkplugs per cylinder.

Maybe someone here on BITOG who knows more about this can verify this requirement.
Also, aircraft piston engines run at a constant speed most of the time. Car engines keep changing their speeds.
 
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Some honest info


 

Red91

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Some honest info


The last link is to a forum of questionable accuracy at best. None of the information in those links explains why you cant run something like Phillips xc in an old car or a compressor pump. All of the arguments are about why you cant run auto oil in an aircraft (or theoretically why you can). I understand why aviation oil is recommended for aircraft. I still haven't found a reason why you couldn't run aviation oil in a flathead Cadillac, a lawnmower or a compressor pump. 🤷‍♀️
 
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The real question is why you would want to run such an oil in a passenger car. Nothing is quite so backwards as GA and the current piston oils reflect that. A name-brand, fully formulated PCMO is light years ahead of what you're asking about.

This question has come up before now and then and I'm surprised you haven't seen those threads. Often it is in the context of the notion that because it's used in aviation (much like "the military uses it" or "it's used on the space shuttle") it is somehow superior. Nothing could be further from the truth, they have different goals and different objectives. I think either Tom NJ or MolaKule gave a better technical description as to why aviation oils are inferior to PCMO.

If you want to use it in a compressor then go ahead, but why deliberately sabotage your lawn mower or your old Cadillac? You're not gaining anything, only losing the advantages of today's superior technology in an oil.
 
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I was of the understanding that aviation oil had little antiwear additives, like zinc or phosphorus ( as to not foul plugs). And that was of little concern since aircraft engines are torn down and rebuilt on a schedule long before wearing out, unlike an auto engine.

IIRC , member cujet had pics of a Lycoming camshaft with the lobes worn down due to this.
 

Red91

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The real question is why you would want to run such an oil in a passenger car. Nothing is quite so backwards as GA and the current piston oils reflect that. A name-brand, fully formulated PCMO is light years ahead of what you're asking about.

This question has come up before now and then and I'm surprised you haven't seen those threads. Often it is in the context of the notion that because it's used in aviation (much like "the military uses it" or "it's used on the space shuttle") it is somehow superior. Nothing could be further from the truth, they have different goals and different objectives. I think either Tom NJ or MolaKule gave a better technical description as to why aviation oils are inferior to PCMO.

If you want to use it in a compressor then go ahead, but why deliberately sabotage your lawn mower or your old Cadillac? You're not gaining anything, only losing the advantages of today's superior technology in an oil.[QUOTE/].

I looked through 14 pages of threads , dating back to 2014 in this section alone and found no such subject.
I'm well aware of the benefits of modern automotive oil in modern automotive engines. I haven't found a satisfactory answer to my theoretical question and that's why I'm trying to discuss it. The blanket statement of "why would you want to " is not a conducive answer to the proposed question. If you dont know that's fine. I don't either and that's why I'm asking. I have been offered a free Honda pressure washer wish an oil leak that hasn't run in several years. Maybe I want to get it running and play with it during my free time. Maybe I'm going to attempt my compressed air project with it since the mower didn't pan out. Sometimes, a person just wants to tinker for the sake of tinkering, and that's ok.
 

Red91

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I was of the understanding that aviation oil had little antiwear additives, like zinc or phosphorus ( as to not foul plugs). And that was of little concern since aircraft engines are torn down and rebuilt on a schedule long before wearing out, unlike an auto engine.

IIRC , member cujet had pics of a Lycoming camshaft with the lobes worn down due to this.
Depending on which lycoming it is, the oil is supposed to be supplemented with an approved additive to prevent cam wear. From what I've read, aircraft piston engines dont wear out due to oil, they wear out due to infrequent use and corrosion.
 

Red91

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With the way my Lycoming consumes oil, I'd rather use an oil without troublesome ash creating additives. :)
Just curious, what do you use? In my reading, Phillips xc seems to be very popular and it's quite a bit cheaper than aeroshell. Can you provide any insight on the topic of my question? I'm not seeing why, if an older car engine can operate fine in bon detergent oil, it couldn't operate fine with aircraft oil. 🤷‍♀️
 
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If one had a Chevy engine from 1963, some aviation oil would be better than no oil. Aviation oil is normally a higher viscosity number too, 20-50 is about the norm, or straight 50 weight. I just abide by the adage if not mixing either, auto or plane.

I normally use Phillips multi grade aviation oil, 20-50, but use Aeroshell at times, then even 100w at times in the Summer. I use Camguard most if the time, though I think it’s more important to fly regularly. I currently have a Lycoming IO-390 with just under 200 hours since factory new.
 
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The commonly used kinematic viscosity is defined as a measure of the restrictive
flow of a fluid under gravitational force, its not a measurement of thickness...

The SI unit for kinematic viscosity is one meter squared per second and is
equivalent to 10,000 St. Usually, centistokes (cSt) is used (1 cSt =0.01 St = 1 mm2/s)

AeroShell Oil Sport Plus 4 10w40
94.2cSt @40C
14.4cSt @100C

Aeroshell Oil 15W 50 is a semi-synthetic multigrade ashless dispersant
oil blend of a mineral oil and synthetic hydrocarbons with an additive
package.

AeroShell Oil 15W-50
140cSt @40C
19.6cSt @100C

AeroShell (straight mineral) They are blended from selected high
viscosity index base stocks and contain a minimum quantity of
additives.

AeroShell Oil 65 (30grade)
90.9cSt @40C
11.8cSt @100C

AeroShell Oil 80 (40grade)
150cSt @40C
14.6cSt @100C

AeroShell Oil 100 (50grade)
230cSt @40C
19.7cSt @100C

AeroShell Oil 120 (60grade)
380cSt @ 40C
24.8 @ 100C

AeroShell 'W' ashless dispersant with non-metallic dispersant additives.

AeroShell Oil W65 (30grade)
91cSt @ 40C
12cSt @ 100C

AeroShell Oil W80 (40grade)
113cSt @ 40C
14.0cSt @ 100C

AeroShell Oil W80 Plus and W100 Plus are single-grade ashless
dispersant with the extra anti-wear and anti-corrosion additive
package of AeroShell Oil 15W-50.

AeroShell Oil W80 Plus (40grade)
113cSt @ 40C
14.0cSt @ 100C

AeroShell Oil W100 (50grade)
200cSt @ 40C
20.2cSt @ 100C

AeroShell Oil W100 Plus (50grade)
195cSt @ 40C
19.9cSt @ 100C

AeroShell Oil W120 (60grade)
270cSt @ 40C
24.8cSt @ 100C

Semi-Synthetic oils use a blend of mineral oil and a synthetic
hydrocarbon oil.

Due to the naturally high viscosity index of the synthetic oil - it's
viscosity changes less with temperature when compared to mineral oils
- there is no need to add a viscosity index improver.

Another advantage of using a semi-synthetic oil is that the synthetic
component of the oil has a higher thermal stability and therefore
degrades at a slower rate than mineral oils. This leads to the oil
both performing as an effective lubricant for longer and also
producing less acidic compounds, the byproducts of oil degradation,
which in turn reduces the risk of acid attack in the engine.

AeroShell Oil W 15W-50 is virtually the only semi-synthetic aviation
mutigrade on the market at present, and has given years of excellent
performance throughout the world.

The obvious question is, "Why not produce a fully synthetic oil if it
so good?".

The answer is simply that, unlike automotive engines, aviation engines
run on 100LL (Avgas) which contains a much higher concentration of
Lead than ordinary 4 star automotive fuel. The combustion of this fuel
inevitably leads to Lead getting into the oil in the crankcase where
it could form Lead deposits, and may lead to subsequent failure.
However if the oil has a mineral oil content to it (either a fully
mineral oil, or a semi-synthetic) then the Lead is dissolved by the
oil, whereas a fully synthetic oil does not have the capacity to do
this.

One of the advantages of using AeroShell Oil W 15W-50 comes when the
aircraft is not flown frequently as the oil contains both a corrosion
inhibitor and an anti scuffing additive (LW16702) to help the
occasional flyer.

If the aircraft cannot be flown with the frequency required to keep
the oil 'dry' (a minimum of 1/2 hour cruise every 2 weeks), the
corrosion inhibitor will suppress the formation of any corrosion
during periods of inactivity, which would otherwise form due to the
action of acids and water.

Furthermore, once the aircraft engine is started up after being
inactive, the anti scuffing additive will have coated all the internal
metallic surfaces with a molecular layer so that metal to metal
contact is prevented if there is no oil present. This is particularly
important during the first few seconds after start up as the oil pump
will not pump oil to all the extremities of the engine immediately.

Again not all oils contain these additives, but combined with the
natural advantages of using a semi-synthetic oil, we believe that
AeroShell Oil W 15W-50 represents the premium quality choice in the
aviation piston engine oil market.


Phillips
20W 50 Phillips Anti Rust
176 cSt @ 40°C
19.1 cSt @ 100°C;
Cold Cranking Viscosity, cP @ -15°C 8865

100AD Phillips Type A
204 cSt @ 40°C
20.2 cSt @ 100°C

120AD Phillips Type A
257 cSt @ 40°C
23.4 cSt @ 100°C

20W 50 Phillips Type M
166 cSt @ 40°C
19.5 cSt @ 100°C;

Type A 100AW, has a stated additive, which is the Lycoming additive.

100AW Phillips Victory
189 cSt @ 40°C
19.5 cSt @ 100°C

X/C mineral basestock

25W 60 Phillips X/C
245 cSt @ 40°C
24.8 cSt @ 100°C
Cold Cranking Viscosity @-10ºC cP 8200

20W 50 Phillips X/C
159 cSt @ 40°C
19.8 cSt @ 100°C
Cold Cranking Viscosity @-10ºC cP 5200
 
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BusyLittleShop, why do you just cut-and-paste from other sites? What does your post mean in regards to the OP's question, can you digest it all and relate how it applies? It says why aviation oil is good for GA piston engines but why is it bad for automobiles?
 

Red91

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I've yet to have anyone directly answer my question. I already understand what aviation oil does for aviation engines. My question is what's the harm in using it for short(ish) intervals in older automotive engines, ope and compressor pumps? In reading more on av forums, I've found quite a few members who claim to have run the 50 grade oils in motorcycles with good results. Of course, I cannot rely on their claims. For all I know it never happened.

Seems everyone here can beat dexos like a dead horse, but no knows or is willing to answer my question. I guess I'll just experiment and see what happens. 🤷‍♀️
 
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Again, why possibly sabotage your car/equipment by using an oil that carries no licenses, approvals nor certifications appropriate for the use? Are you just swimming in this oil and have a burning desire to use it?

Whether anyone can give you specifics is one thing, but the greater reality is that it is not intended for, nor is it rated for any OPE or automotive use unless it also has an API license, which I doubt.

And I'm not sure where your little thingy about dexos comes in.
 

Red91

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Again, why possibly sabotage your car/equipment by using an oil that carries no licenses, approvals nor certifications appropriate for the use? Are you just swimming in this oil and have a burning desire to use it?

Whether anyone can give you specifics is one thing, but the greater reality is that it is not intended for, nor is it rated for any OPE or automotive use unless it also has an API license, which I doubt.

And I'm not sure where your little thingy about dexos comes in.
There have been dexos threads a dime a dozen that are overflowing with rehashed answers. I cant get one here. The "equipment " I'm playing with is junk anyway, so if I come away with an answer, I gained knowledge as a trade off.
 
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