Honest question about aviation oil

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Red91

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From years and years of practical experience, I really can't tell a wear difference between any of the aviation oils. Other than the AS 15W-50 leaves somewhat fewer deposits under the valve cover. It seems to me, oil change frequency is far more important than brand.

These guys get 2380 turbine oil. During a recent engine "midlife" the BR710's looked perfect inside. So the 2380 worked just fine.


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I contacted the airport for pricing. Waiting to hear back. They carry 100, w100 and 15w50. I'd probably try the multi grade since it has the lycoming antiwear package, ashless dispersant and half synthetic base stock. Seems like that would be the most practical of the choices, especially considering the toys are pull start, and I dont think I want to pull start with straight 50 in the sump lol.
 

MolaKule

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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?

What vehicle and what engine is your classic car?

Why would one use an aviation piston oil when there are classic car oils formulated specifically for those classic cars?

A common misconception is that aviation oils are somehow superior in some way to terrestrial water-cooled engine oils and this is not the case.

An aviation piston engine oil has approx. 250 ppm of phosphate anti-wear, about 90 ppm of calcium as a mild detergent, about 5 ppm of ZDDP which acts as a secondary anti-oxidant. about 5 ppm of sodium as an anti-rust agent, and an ashless dispersant; so they are not completely ashless. The low treatment levels of organometallic elements keeps ash and deposits at a minimum.

Lead loading of aviation piston engine oils is around 185 ppm of lead per hour of operation, and this is where most organometallic deposits come from.

Aviation piston engine oils usually derive their anti-wear and anti-scuff capabilities by virtue of a high viscosity oil film and the phosphate additive.

Terrestrial water-cooled engine oils need about 3.5X that amount of phosphate anti-wear because of the reduced oil film thickness in lower viscosity oils.

As another poster stated, these air-cooled engines go through some wild swings in terms of temperature fluctuations whereas a terrestrial water-cooled engine maintains an almost constant temperature after warm-up.

Bottom line is, it is not recommended that you use aviation piston engine oils in any terrestrial machine.
 
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And what the other way around?

Modern low saps PCMOs in avio engines?
I have asked/opened that topic twice in the past...

ACEA C4 has set ash level @0.5 as maximum...
 

MolaKule

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And what the other way around?

Modern low saps PCMOs in avio engines?
I have asked/opened that topic twice in the past...

ACEA C4 has set ash level @0.5 as maximum...

Where, didn't see it.

Regardless, there are completely different sets of base oils and additive compositions used for each application, so there is no implied cross-application.
 

Red91

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What vehicle and what engine is your classic car?

Why would one use an aviation piston oil when there are classic car oils formulated specifically for those classic cars?

A common misconception is that aviation oils are somehow superior in some way to terrestrial water-cooled engine oils and this is not the case.

An aviation piston engine oil has approx. 250 ppm of phosphate anti-wear, about 90 ppm of calcium as a mild detergent, about 5 ppm of ZDDP which acts as a secondary anti-oxidant. about 5 ppm of sodium as an anti-rust agent, and an ashless dispersant; so they are not completely ashless. The low treatment levels of organometallic elements keeps ash and deposits at a minimum.

Lead loading of aviation piston engine oils is around 185 ppm of lead per hour of operation, and this is where most organometallic deposits come from.

Aviation piston engine oils usually derive their anti-wear and anti-scuff capabilities by virtue of a high viscosity oil film and the phosphate additive.

Terrestrial water-cooled engine oils need about 3.5X that amount of phosphate anti-wear because of the reduced oil film thickness in lower viscosity oils.

As another poster stated, these air-cooled engines go through some wild swings in terms of temperature fluctuations whereas a terrestrial water-cooled engine maintains an almost constant temperature after warm-up.

Bottom line is, it is not recommended that you use aviation piston engine oils in any terrestrial machine.
I've pretty well concluded that I'm not going to use it in a water cooled engine.
 
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What vehicle and what engine is your classic car?

Why would one use an aviation piston oil when there are classic car oils formulated specifically for those classic cars?

A common misconception is that aviation oils are somehow superior in some way to terrestrial water-cooled engine oils and this is not the case.

An aviation piston engine oil has approx. 250 ppm of phosphate anti-wear, about 90 ppm of calcium as a mild detergent, about 5 ppm of ZDDP which acts as a secondary anti-oxidant. about 5 ppm of sodium as an anti-rust agent, and an ashless dispersant; so they are not completely ashless. The low treatment levels of organometallic elements keeps ash and deposits at a minimum.

Lead loading of aviation piston engine oils is around 185 ppm of lead per hour of operation, and this is where most organometallic deposits come from.

Aviation piston engine oils usually derive their anti-wear and anti-scuff capabilities by virtue of a high viscosity oil film and the phosphate additive.

Terrestrial water-cooled engine oils need about 3.5X that amount of phosphate anti-wear because of the reduced oil film thickness in lower viscosity oils.

As another poster stated, these air-cooled engines go through some wild swings in terms of temperature fluctuations whereas a terrestrial water-cooled engine maintains an almost constant temperature after warm-up.

Bottom line is, it is not recommended that you use aviation piston engine oils in any terrestrial machine.

Very well said sir 👍
 

Red91

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Very well said sir 👍
Well, actually no it isn't. This was a long winded reply that only made one point: the heavy aviation oil can rely on very low levels of metallic additives because of the thicker film strength of the base oil. That doesn't correlate to the oil being an inappropriate choice for air cooled terrestrial engines. The focus on liquid cooled car engines has kind of become moot as I've started that my focus is on air cooled ope. None of that reply makes a case against using aviation oil in an air cooled ope engine. The only argument I've encountered thus far is the point of possible seal compatibility issues, which really isnt a concern for me in regard to my toys. All that was said was it's not recommended, but without an explanation as to why.
 

Astro14

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Well, actually no it isn't. This was a long winded reply that only made one point: the heavy aviation oil can rely on very low levels of metallic additives because of the thicker film strength of the base oil. That doesn't correlate to the oil being an inappropriate choice for air cooled terrestrial engines. The focus on liquid cooled car engines has kind of become moot as I've started that my focus is on air cooled ope. None of that reply makes a case against using aviation oil in an air cooled ope engine. The only argument I've encountered thus far is the point of possible seal compatibility issues, which really isnt a concern for me in regard to my toys. All that was said was it's not recommended, but without an explanation as to why.

Actually, it is well said, and answers your question.

Red, your original post asked about using Aviation oil in classic cars and compressors. Now that your original question was answered, definitively, you want to change the question to air cooled power equipment?

The only reason I can imagine that you keep changing the question, is that you want to keep the discussion going, the discussion in which you criticize every response.

Lock time.
 
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