Keep same oil filter for one more oil change?

[kmyfm20s]

With an engine that has a perfectly healthy history you will be fine not changing the filter with oil that has 15 hours on it. Your changing the oil out concern of acid formation and reducing corrosion potential. After all you will eventually change the filter at the otherwise normal engine time interval to inspect it.

[carusoam]

Two ends of the spectrum....

1) Not changing oil and filter for a year and 100hrs on the oil and added quarts....

2) Changing the oil at 15hr... wondering if skipping the filter change is important....

3) In the end...  it is about changing the oil... the filter is holding an extra quart...

4) if you emptied the filtered to get the old quart out....I see your point...

5) if you didn’t touch the filter, and left the old quart in... you probably didn’t get your money’s worth...

6) Past the end... is it going to make a difference on the spectrum from changing often, to changing annually..?

7) If you are trying to go way past TBO... yes, it will make a difference.

8) If something else is going to kill the plan.... like not making it to TBO for some other reason...  this could be focusing on the pennies... and letting the dollars get by...

9) There is one substitute for flying often... and that requires pickling, and dry air...

10) Do the best you can with what you have...   

PP thoughts only, pondering... what does a proton sound like when it is relaxing?

Best regards,

-a-

[RobertGary1]

I think too if you’ve ever opened a filter you’d feel more comfortable with saving the filter for a 50+ hours. Unless the engine has problems it may look new. Even with my factory new engine I may find 1 nearly microscopic spec. Not worth fearing a filter plug with that every 50 hours. It’s more about looking for trend changes. 

[EricJ]

7 hours ago, ilovecornfields said:

Sorry, but I didn’t see an explanation to go over my head. I asked you to name the dangerous process that is invisible on a 25 hour oil change but readily apparent on a 50 hour oil change and instead you provided a personal attack.

If you took that as a personal attack I suspect you have some pretty thin skin.   

The process had been previously described so I didn't think it needed a repeat.

 

7 hours ago, ilovecornfields said:

I’m not sure what I don’t have “any experience” with. I’ve changed my oil, I just choose not to do it and I explained why. It really wasn’t that difficulty a task to do. Because I acknowledge I’m not an expert at something and delegate the task to someone who is that makes me a fool? Do you not understand that part of doing more frequent oil filter changes is to examine the engine and look for problems? You think I would get more out of looking at the engine than my experienced A&P/IA?

The relevant process is cutting open the filter and inspecting it for metal and debris, as previously described in this very thread.   If the filter hasn't had enough time on it to collect a representative sample of what the engine is doing, especially since the events that generate the metal and debris may not be uniformly distributed in time, then it is less likely that you'll get good information from it.   You can look at the rest of the engine all you want, or send in oil samples or take you A&P to lunch, but the point being addressed was the time between filter changes in the context of getting useful information from inspecting it.   You suggested just cutting inspection criteria thresholds in half, but the particles are quantized, and when things are good the number of captured particles is very small.   This means that quantization noise comes in to play, both in size (since the filter takes out anything above a specific size) and quantity.   I tried to explain it with a couple of relevant analogies; SNR since the quantization and filter function puts a lower limit on the detectable particle size and because the numbers start very small, and statistics since reducing the operational time of the filter is like reducing N in a statistical sample size.   You can reduce your thresholds, but the data won't be as good and potentially not useful at all.

When I tried to explain it this way your response was:

"I get the argument, but it just seems like a rationalization for being lazy instead of a real scientific argument based on reality."

which a thin-skinned person may have taken as a personal attack made by you.   So I understand why you are sensitive to such things.   Life must be difficult for you.

 

7 hours ago, ilovecornfields said:

With respect to interpreting GC-MS data, I do have some experience. I used to run my own and interpret them when I was doing chemistry research (I did mention that if you’ll recall). I even ran my own proton NMRs and learned how to tune it by listening to the sounds of the protons relaxing. I’ve also spent 20 years working with statistical analysis so I think I have some experience there, too.  But I guess I don’t have the unique experience you do which make you able to definitively say exactly when oil filters should be changed, who should do it and why anyone who disagrees is a fool.

Sorry you don't get it.  It is probably best that you don't change your own oil.

[ilovecornfields]

1 hour ago, carusoam said:

PP thoughts only, pondering... what does a proton sound like when it is relaxing?

Starts at 16:00

 

[ilovecornfields]

22 minutes ago, EricJ said:

The relevant process is cutting open the filter and inspecting it for metal and debris, as previously described in this very thread.   If the filter hasn't had enough time on it to collect a representative sample of what the engine is doing, especially since the events that generate the metal and debris may not be uniformly distributed in time, then it is less likely that you'll get good information from it.   You can look at the rest of the engine all you want, or send in oil samples or take you A&P to lunch, but the point being addressed was the time between filter changes in the context of getting useful information from inspecting it.   You suggested just cutting inspection criteria thresholds in half, but the particles are quantized, and when things are good the number of captured particles is very small.   This means that quantization noise comes in to play, both in size (since the filter takes out anything above a specific size) and quantity.   I tried to explain it with a couple of relevant analogies; SNR since the quantization and filter function puts a lower limit on the detectable particle size and because the numbers start very small, and statistics since reducing the operational time of the filter is like reducing N in a statistical sample size.   You can reduce your thresholds, but the data won't be as good and potentially not useful at all.

I’m not sure you know me well enough to comment intelligently on the thickness of my skin, but with respect to your argument above, in order for that to be true you would have to be describing a catastrophic process which makes an undetectable amount of metal at 25 hours but a significant amount at 50 hours. I’m not aware of such a process but then I’ve been pretty clear from the start that I’m not an A&P.
 

Even if what you are saying IS true, you would still be looking at the engine compartment half as often so you would be arguing that this particular process which you have yet to describe is more important than the inspection of the engine compartment which most seem to agree is very important.

You are correct that I don’t get “it” with respect to your argument and rationalization and I get the feeling I’m not going to. You are also correct that I’m better off not changing my own oil. My mechanic does an excellent job, does a thorough inspection, leaves no mess and frees up my time to do other things that I enjoy. 
 

At least we found two things we could agree on!

Edited March 13, 2021 by ilovecornfields

[RobertGary1]

For those advocating changing the filter during a 6 month oil change that may only have a few hours on it; do you also pull the pick up screen as described in the maintenance manual? I only do that every 3-4 oil changes. Never found anything in it. 

[EricJ]

2 hours ago, ilovecornfields said:

I’m not sure you know me well enough to comment intelligently on the thickness of my skin,

And yet my comments above got to you.   You've been observed overreacting to posts here multiple times before, so that was the basis for the comment.

2 hours ago, ilovecornfields said:

but with respect to your argument above, in order for that to be true you would have to be describing a catastrophic process which makes an undetectable amount of metal at 25 hours but a significant amount at 50 hours. I’m not aware of such a process but then I’ve been pretty clear from the start that I’m not an A&P.

No.   As previously described in this thread several times, the statement you've responded to deals with inspecting the filter for metal and debris.  This involves cutting the filter open and cutting the filter media out and removing it for inspection.    This is supposed to be done every time the filter is removed.   The difference is not between none at 25 and significant at 50, which you would more likely know if you had actually ever done this enough to be knowledgeable on the topic.   Even a typical healthy engine produces a few flakes and chunks that should be evaluated and some healthy engines produce a fair amount depending on what's going on.   The maximum allowed amount is actually surprisingly large, but when observing trends on a particular engine comparisons will be most valid if done on the same intervals, but if the interval is too short then the quantity of metal particles can easily be small enough to make interpretation indeterminate or very difficult.

e.g., +/- 10 flakes creates a large potential error when the total quantity is 20, but not so much when the total is 200.   Keeping the filter in long enough increases the observation time as well as the quantity of the item of interest and increases the reliability of the resulting interpretation.   Once again, an easily understood analogy is increasing the confidence interval in a statistical process by making sure the number of observations is significant.   It is not a particularly difficult concept.

Sometimes there is a recommendation to change the filter after a short time to verify that it is not collecting large quantities of flakes in a short time, but those are exceptional situations and not part of normal oil change intervals.

2 hours ago, ilovecornfields said:

Even if what you are saying IS true,

It is.

2 hours ago, ilovecornfields said:

you would still be looking at the engine compartment half as often so you would be arguing that this particular process which you have yet to describe is more important than the inspection of the engine compartment which most seem to agree is very important.

If you think the process you responded to is undescribed then you didn't read or comprehend before posting, which does explain some things.   I think you're particularly confused because even if the oil is changed without removing the filter it certainly wouldn't prevent "looking at the engine compartment", as in many (most?) airplanes the cowl comes off to change the oil, anyway, whether or not the filter is changed.   Regardless, it's still not relevant to the point you responded to, which was how leaving the filter in longer improves the ability to assess and interpret the collected debris.

Somebody else cited the Lycoming operator's manual, which actually says to change the filter every-other 50 hour oil change interval, so 100 hours between filter changes.   I think most do it more often than that, as in every oil change, but the point is really that it needs to be in long enough that the collected metal and debris provides a sample that can be reliably interpreted of what the engine is doing.   The post you originally responded to just said 25 hours is too short, which I mostly agree with, and Lycoming seems to as well.   If you disagree, then by all means make sure your A&P is changing the oil and filter at least every 25 hours, or whatever makes you comfortable.  If as you say more frequent inspections are better for you, then do it every 10 hours, or perhaps even every flight.   Some might think that excessive, but by all means you do you.

2 hours ago, ilovecornfields said:

You are correct that I don’t get “it” with respect to your argument and rationalization and I get the feeling I’m not going to. You are also correct that I’m better off not changing my own oil. My mechanic does an excellent job, does a thorough inspection, leaves no mess and frees up my time to do other things that I enjoy. 
 

At least we found two things we could agree on!

 

[Andy95W]

I frankly suspect the two of you have much more in common than not, and would likely enjoy each other’s company and discussions much more in person over a beer than on the internet.

[Tim Jodice]

8 minutes ago, Andy95W said:

I frankly suspect the two of you have much more in common than not, and would likely enjoy each other’s company and discussions much more in person over a beer than on the internet.

I wish I could thank you and like the post.

[Tim Jodice]

On 3/12/2021 at 10:18 AM, N201MKTurbo said:

Because when I was using my airplane to commute to work, I didn't have time to remove the cowl and change the filter. I could fill it back up in about 5 minutes. The filter still got changed 3 or 4 times a year.

 

There is a lot more crud sitting in the sump than in a drained filter...

This is what I do for the same reason. Oil every 25-30 hours, filter every other and sump screen every 4th oil change. Fortunately so far they both have come out clean. I do the same process as 

Summer time is the peak season for my business and at that time I am doing an oil change every 2-3 weeks so simply doing a drain and fill saves time. Sounds stupid but after flying/working/flying the last place I want to be is in the hangar. 

[philiplane]

Here's what Lycoming says about oil servicing, filters, and metal analysis. FWIW- both Lycoming and Continental are far less worried about metal in the oil than we are.

SB480F Oil ServicingMetallic Solids Identification .pdf

Edited March 14, 2021 by philiplane

[ilovecornfields]

On 3/13/2021 at 1:43 PM, EricJ said:

And yet my comments above got to you.   You've been observed overreacting to posts here multiple times before, so that was the basis for the comment.

No.   As previously described in this thread several times, the statement you've responded to deals with inspecting the filter for metal and debris.  This involves cutting the filter open and cutting the filter media out and removing it for inspection.    This is supposed to be done every time the filter is removed.   The difference is not between none at 25 and significant at 50, which you would more likely know if you had actually ever done this enough to be knowledgeable on the topic.   Even a typical healthy engine produces a few flakes and chunks that should be evaluated and some healthy engines produce a fair amount depending on what's going on.   The maximum allowed amount is actually surprisingly large, but when observing trends on a particular engine comparisons will be most valid if done on the same intervals, but if the interval is too short then the quantity of metal particles can easily be small enough to make interpretation indeterminate or very difficult.

e.g., +/- 10 flakes creates a large potential error when the total quantity is 20, but not so much when the total is 200.   Keeping the filter in long enough increases the observation time as well as the quantity of the item of interest and increases the reliability of the resulting interpretation.   Once again, an easily understood analogy is increasing the confidence interval in a statistical process by making sure the number of observations is significant.   It is not a particularly difficult concept.

Sometimes there is a recommendation to change the filter after a short time to verify that it is not collecting large quantities of flakes in a short time, but those are exceptional situations and not part of normal oil change intervals.

It is.

If you think the process you responded to is undescribed then you didn't read or comprehend before posting, which does explain some things.   I think you're particularly confused because even if the oil is changed without removing the filter it certainly wouldn't prevent "looking at the engine compartment", as in many (most?) airplanes the cowl comes off to change the oil, anyway, whether or not the filter is changed.   Regardless, it's still not relevant to the point you responded to, which was how leaving the filter in longer improves the ability to assess and interpret the collected debris.

Somebody else cited the Lycoming operator's manual, which actually says to change the filter every-other 50 hour oil change interval, so 100 hours between filter changes.   I think most do it more often than that, as in every oil change, but the point is really that it needs to be in long enough that the collected metal and debris provides a sample that can be reliably interpreted of what the engine is doing.   The post you originally responded to just said 25 hours is too short, which I mostly agree with, and Lycoming seems to as well.   If you disagree, then by all means make sure your A&P is changing the oil and filter at least every 25 hours, or whatever makes you comfortable.  If as you say more frequent inspections are better for you, then do it every 10 hours, or perhaps even every flight.   Some might think that excessive, but by all means you do you.

 

Sorry, just saw this. I guess I’m not sure how you define what the appropriate reaction to something is. There are some incredibly dumb things that get said on here, so I would argue that the reaction is sometimes proportional to absurdity of the original content.

Any thoughts on this current thread regarding large amounts of metal found in the filter? Is that something you would have wanted to wait an additional oil change interval to find out? Seems like this is an example of exactly what I was talking about. Even though I know nothing about oil. Or changes (although my son is attending online puberty classes so we’re learning a lot about changes). 

[EricJ]

Just now, ilovecornfields said:

Any thoughts on this current thread regarding large amounts of metal found in the filter? Is that something you would have wanted to wait an additional oil change interval to find out? Seems like this is an example of exactly what I was talking about. Even though I know nothing about oil. Or changes (although my son is attending online puberty classes so we’re learning a lot about changes). 

I did go through a period where I had large amounts of metal in the filter, over repeated oil changes.   I had consulted both the local Lycoming rep and the engine shop that had done a teardown a few hundred hours previous.  Both said to just monitor it during regular oil changes, which I did.   This is also consistent with Lycoming's written guidance in this area.   After one particular event I did a filter change after only about 10 hours (on the recommendation of somebody), and it was inconsequential, because there just wasn't enough time on the filter to really be able to tell much.   So the advice to put more time on the filter is pragmatic, and also makes sense from a statistical and analytical pov.

It ultimately turned out that my prop governor was failing and destroying itself internally.   I've seen very little metal in the filter since the governor was changed.

[Will.iam]

here is an interesting data point. I started using a dehumidifier on my engine in between flights since my last oil change and on my last oil analysis Blackstone even commented that they detected no water in the oil sample I had sent to them.  That was 25 hours on the sample with flying the airplane at least once every 3 weeks or more FWIW.

[kerry]

If I remember correctly when oil filter kits were first introduced on a Lycoming you could extend your oil change to 50 hours vs. 25 hours with screens only.  Personal I check my screens every 50 hours and change my oil every 25 hours as indicated in my owners manual.  With that said I would say you're pretty safe chaining your filter every 50 hours.