What Oil Do You Run?

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Rich
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Re: What Oil Do You Run?

Post by Rich »

I don't mean to incur ire here, just humor. On the MC forum I participate in, there is a section titled "Never-Ending, Pointless, Recurring Threads". Any thread that involves oil immediately gets put in this section. It doesn't inhibit continued discussion on the thread, it just focuses on the impossibility of actually reaching any sort of conclusion. In the case of motorcycles, there are orders of magnitude more choices folks can make, so these continue for, literally, years.

The question here is well-asked, by the way, simply asking "what oil do you run?" rather than asking the impossible "which oil is best?". I feel the latter has no answer.

Here's an interesting variable: All those years I was based in the Puget Sound area it was normal (hangared or not) on the first flight of the day to see water drops on the dipstick. Right after the engine work in '15 we moved here to a higher and drier climate and I never see this any more. Also this was when I started using Cam Guard. So I changed 3 test conditions at once to get to this result. :scratch:
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Kyle
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Re: What Oil Do You Run?

Post by Kyle »

I use Aeroshell W100 with Camgaurd based on recommendations from Savvy, an A&P, and another DA40 pilot. Note that I'm based in a warm climate and would rarely, if ever, have the need for a below-freezing start.

Rob,
I wonder what it would take to get Blackstone or one of the other oil labs to release their oil data for specific aircraft types or engines. They would already have all the data you would want for an oil type study. It could be easily aggregated by oil type for a given engine or aircraft type if the data was available. Or maybe they do this already and I just don't know about it, seems like a natural step for them to take given all the data they have.
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Re: What Oil Do You Run?

Post by Pascal »

I use Aeroshell 15W50. It gets cold in Quebec in the winter, but I do not expect to have much time for flying in the winter months. I might add Camguard or switch to another oil, we'll see. I only have had my airplane since late April.

I too am an avid motorcyclist and I have read way too much about this topic. My take aways from all these readings are:
1) Your engine getting a weekly workout so that the various engine parts are oiled and protected is more important than the brand of oil per say, as long as you are within the temperature range appropriate to where you fly.
2) Synthetic is better than fossil.
3) Replacing the oil and filter on a regular basis is a lot cheaper than overhauling an engine.
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Re: What Oil Do You Run?

Post by Sandy »

Does it matter if you mix oils?
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Lou
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Re: What Oil Do You Run?

Post by Lou »

Sandy wrote:Does it matter if you mix oils?
Yes, it does. For instance, you cannot mix Phillips x/c with Aeroshell. Folks who know more than me can explain which oils are incompatible. This is one of the reasons I changed to Aeroshell 15W50, because it seems to be more common in Canada, and you don't need additive.
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Re: What Oil Do You Run?

Post by rwtucker »

Kyle wrote:Rob,
I wonder what it would take to get Blackstone or one of the other oil labs to release their oil data for specific aircraft types or engines. They would already have all the data you would want for an oil type study. It could be easily aggregated by oil type for a given engine or aircraft type if the data was available. Or maybe they do this already and I just don't know about it, seems like a natural step for them to take given all the data they have.
Oil labs possess some of the data necessary to illuminate this question. There would be shortcomings. The actual data supplied to the labs on the oil analysis form may not be that accurate and I suspect that there would be a large number of missing variables. In most cases, we would have only indirect pre-indicators of failure. On the other hand, a lab-driven analysis by engine serial number following the overhaul cycles and TBO hours, controlled for oil type, oil hours, engine type, etc. might be informative, although it would be less than definitive.

I think we could do better in DAN.

If engine life is the dependent variable, then the family of independent variables other than oil type is large. IVs such as hours between changes, filter (hours and type), mean and high temps (CHT, OT, EGT, OAT) [probably interval bracketed] mean and high percent of power, etc. would need to be controlled for in a perfect design. Ambient atmospheric relative humidity is even a consideration as an IV (the above oil lab design could test for progression to failure by geographic region, comparing aircraft hangered in the southwest versus the southeast, for example; “hangered versus not” is also a potential IV). We would need definitions for the DV as well; perhaps we would run the analysis under several definitions such as mechanical failure, oil analysis indicating impending failure, failed compressions, etc. I see a few constraints here as well, most of which can be overcome with good design work.

Given the data limitations, I can't see how we could create the kind of robust experimental design that would give a hard answer to these oil related questions. I do think that some quasi-experimental designs would be workable (e.g., multi-factor regressions, regression discontinuity and similar).

A decent study might be based on a sample of DAN members who agree to input G1000 data into a repository (selection biases would be introduced here as well and need to be partially controlled for) along with their personal non-G1000 data.

This might sound complicated. It is not. The design and analysis components are a level of complexity that might get assigned to a base or intermediate-level graduate course in research design. The only software needed is a suite of SPSS (or equivalent) modules and the only input data would be G1000 files linked to the non-G1000 pilot data (e.g., oil type, change intervals, etc.) which could be provided on a linked spreadsheet. The most difficult part of this study might be writing and testing the data creation, management, and validation code. This is all draft level thinking but we could advance it to a project were there enough interest and volunteers.
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Re: What Oil Do You Run?

Post by Sandy »

Lou wrote:
Sandy wrote:Does it matter if you mix oils?
Yes, it does. For instance, you cannot mix Phillips x/c with Aeroshell. Folks who know more than me can explain which oils are incompatible. This is one of the reasons I changed to Aeroshell 15W50, because it seems to be more common in Canada, and you don't need additive.
Lou, thank you for a response, but I was really hoping to hear something specific. After reading your response I "googled" the question, and I found this web page, http://www.aviationpros.com/article/103 ... the-engine

According to it, there is no problem, as all aviation oils meet the same SAE specs. It seems to me, then, that aside from selecting a particular viscosity (typically based on temperature), it is unclear why mixing oils should be problematic.
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Sandy
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Re: What Oil Do You Run?

Post by Sandy »

FWIW, I just found this on the Lycoming site, "The latest revision to Lycoming Service Instruction 1014 gives recommendations for lubricating oils, oil change intervals and engine break-in. Pilots and mechanics should know what weight, type and brand of oil is being used in the engine being serviced. At each oil change, this specific information should be recorded in the engine logbook. Except as a temporary measure in an emergency, different oils should not be mixed. Consistent indiscriminate mixing of oils may create high oil-consumption problems or clogged oil control rings and oil screens."

While that quote supports Lou's response, it hardly sounds very scientific to me, as there is no explanation and merely a suggestion as to what "may" happen, but not "why" it "may" happen.
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Re: What Oil Do You Run?

Post by rwtucker »

Sandy,

The kind of information you mentioned sounds to me like the implications of mixing detergent and non-detergent (break-in) oils, especially if you run a non-detergent for a long period of time and then switch to detergent. Stuff can break loose, they say.
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Re: What Oil Do You Run?

Post by Rich »

Aircraft oils are never detergent compounds, but "Ashless Dispersant". They are formulated to hold contaminants in suspension but not "clean" existing deposits to avoid the issue of switching from straight mineral to "normal" oils. A break-in period could easily be 50 hours or more, plenty of time to form deposits.

A certain amount of mixing oil types is inevitable when switching oils, as a non-trivial amount remains in the engine after draining. Lots of nooks and crannies that don't drain at all or very slowly and the entire internals of the engine is coated with the oil from the last time it was run. How much remains is open for debate, but the engine relies on this oil to remain for some time for lubrication for the next start.
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