You know you're having a bad day when......

[Doug G.]

Yes, I was not contradicting you. For the sake of full disclosure FredG and Doug G are not, to my knowledge, related.

[FredG]

In fact, we barely know each other!

[Anticept]

"Executive blood sample" may be a poor analogy, but even do it does prove a point. When I get my results back from the doctor there is a set point at which he prescribes treatment, not based on some vague art, but on research. The numbers have meaning and action is based in that meaning. Admittedly things change as more data is collected, but I would be extremely upset if the doctor said, "I really can't tell you why I think you should start taking this medicine, and I can't really point to anyone that this has helped, but it is more of an art than a science, so do it anyway."

And we have no data, no parameters, no guidelines for action... and no art school!

 

Alright look at it this way: since rotax does not publish anything about oil sampling, it does give you the freedom to make choices like this! Is it worth it, TO YOU, to spend the extra time and effort on the off chance that you will catch something?

[Doug G.]

I think I have stated my position pretty clearly. My questions have been answered by a lack of answers.

 

In the summer of 1971 I was on a tie gang replacing railroad ties in the mountains of Montana. One of our machines had broken down so we couldn't go out one particular day. The foreman had us go to the rail yard to chop weeds with shovels. Now, I dislike weeds as much as the next person, but they had better and much more efficient ways of doing this and I would not have minded if I was sent out with a sprayer to do it. Of course, we were sent out there to save the forman the problem of figuring out the paperwork for a partial day of work. I would have rather gone home because the work didn't make sense.

If Bryan Carpenter and Mike Busch say that this doesn't make sense, and there is nothing solid from you (its an art) then, to me it is right up there with chopping weeds with a shovel - work that doesn't actually accomplish anything. It is not the money, or the work, or the time, it is the results - which seem negligible at best, unless you are talking about turbine bearings.

[Anticept]

I think I have stated my position pretty clearly. My questions have been answered by a lack of answers.

 

In the summer of 1971 I was on a tie gang replacing railroad ties in the mountains of Montana. One of our machines had broken down so we couldn't go out one particular day. The foreman had us go to the rail yard to chop weeds with shovels. Now, I dislike weeds as much as the next person, but they had better and much more efficient ways of doing this and I would not have minded if I was sent out with a sprayer to do it. Of course, we were sent out there to save the forman the problem of figuring out the paperwork for a partial day of work. I would have rather gone home because the work didn't make sense.

If Bryan Carpenter and Mike Busch say that this doesn't make sense, and there is nothing solid from you (its an art) then, to me it is right up there with chopping weeds with a shovel - work that doesn't actually accomplish anything. It is not the money, or the work, or the time, it is the results - which seem negligible at best, unless you are talking about turbine bearings.

 

I have a better suggestion if you want hard data. Call the oil sampling companies. I can't really give you direct answers to your questions because I have not experienced what you are asking first hand. It's not like they go around publishing this data either.

 

By the way, I don't do SOAPs myself. Just as I previously said, if you are following TBOs, then they really aren't worth it. I've been following TBO myself, although I'm considering starting a trending program and just replace the engine when things start to look suspicious after TBO.

[FastEddieB]

Again, I find this discussion fascinating.

 

I never had any idea there was a debate on the topic - I was led to believe oil analysis was a defacto "good thing".

 

For now, I'll continue to do them.

 

I can imagine a scenario where a sudden jump in chrome or bronze or whatever would, in fact, lead me to investigate further and possibly save me further damage from something who's wear had markedly accelerated. Or even an engine stoppage in flight.

 

But I, too, would love to see data and to hear anecdotes as to how oil analysis has actually saved an owner from more extensive damage, or caught impending failure that might otherwise have gone undetected.

 

Thanks for the discussion!

[WmInce]

Again, I find this discussion fascinating.

 

I never had any idea there was a debate on the topic - I was led to believe oil analysis was a defacto "good thing".

 

For now, I'll continue to do them.

 

I can imagine a scenario where a sudden jump in chrome or bronze or whatever would, in fact, lead me to investigate further and possibly save me further damage from something who's wear had markedly accelerated. Or even an engine stoppage in flight.

 

But I, too, would love to see data and to hear anecdotes as to how oil analysis has actually saved an owner from more extensive damage, or caught impending failure that might otherwise have gone undetected.

 

Thanks for the discussion!

 

I concur with you Eddy.

[Dan Kent]

I have an automotive example that may or may not apply. I started doing oil analysis on my car several years ago, mainly to extend oil change interval. One of my co-workers pickup truck was going out of warranty and he was considering buying an extended warranty. I suggested he might want to have his oil analyzed to see if there were any early warning signs on his engine.

 

He had the analysis performed and they found some antifreeze in his oil. The lab immediately called him and told them of their findings and where specifically to look for the leak as this particular size and make of engine had a history of this problem.

 

The owner took the oil analysis to the dealer and their mechanic looked where the company had suggested. They fixed the problem and gave him another 12 months factory warranty on his engine.

 

In this case the $20 was well spent.

[Rich]

I've had oil analysis performed on my 912 since the 50 hr. mark. I chose not to for the first 25 oil and filter change, as I thought readings may be a little high.

 

The 50 hour change was a good benchmark in my opinion. The 50hr. and 100hr showed normal results compared to the other 912sout there. I always check the magnetic plug and cut the filter open, wash it and put it through a paper paint strainer to check for debris.

 

I take photos of both and save them, just incase they will be needed in the future and log it in the engine log.

 

I also don't know what Rotax says is acceptable but I like to see if there is anything flagged in metal wear in my engine.

If something spikes, I'd consult a Rotax mechanic to see what may need to be done and when.

 

I just feel safer flying knowing the wear pattern of my engine.

 

The cost for four samples and one filter analysis is $119 including postage with the Lab I'm using. Well worth the peace of mind in my opinion.

 

Great thread and links.

 

Rich

 

From this point forward I plan on 50hr intervals.

 

I've followed this thread, listened to the opinions and respect them all, as there are good points raised on both sides of the issue.

 

 

 

 

[Runtoeat]

I visited the Rotax booth at Sebring a few years ago. One of the factory mechanics was there fielding questions. This mechanic worked in the factory durability teardown lab. At the time, I was changing my oil every 100 hours. I asked him what he thought about the Rotax recommended 100 hour oil change interval , based on the teardowns he had done over the years. He smiled, looked around, and said he'd be doing them every 50 hours. I've been doing the changes every 50 hours after this conversation. Besides being cheap insurance, the more frequent changes provide the opportunity to examine the magnetic plug and oil filter.

[Roger Lee]

Hi Dick,

 

This is why we teach 50 hrs. for unleaded fuel (25 hrs for 100LL) in classes even though it says 100 in the manual. It needs a revision. Some things are just poorly documented in some manuals and revision changes are slow.

[Doug G.]

Hi Dick,

 

This is why we teach 50 hrs. for unleaded fuel (25 hrs for 100LL) in classes even though it says 100 in the manual. It needs a revision. Some things are just poorly documented in some manuals and revision changes are slow.

If I understand what you are saying it is because a Rotax mechanic changes oil at 50 you do too. No facts or reason. I was going to wait until 100, but the oil began to look worse, based on that I changed it early. I will be changing somewhere around 50, while the oil still looks new, but the 100 mark gives me some leeway. That's a reason - still no facts.

[Roger Lee]

Hi Doug,

 

You can't tell how well an oil is working or how it's chemical properties are holding up just by looks. Blackened oil is nothing more than oil doing its job. Removing impurities and the black comes from carbon. There is no way for any of us to tell on the oil's break down based solely on color. The only way to really tell about the oil's worth is have have it tested. The City of Tucson tried that. Test all oil and change it based on the results of the oil break down. They found out it was far cheaper to just change the oil on a schedule.

[Tom Baker]

If I understand what you are saying it is because a Rotax mechanic changes oil at 50 you do too. No facts or reason. I was going to wait until 100, but the oil began to look worse, based on that I changed it early. I will be changing somewhere around 50, while the oil still looks new, but the 100 mark gives me some leeway. That's a reason - still no facts.

 

Doug, IIRC the oil change intervals in the manual used to be 25 and 50, then changed to 50-100 when they added several different synthetic oils to the approved fluid list. When I started working on Rotax Pennzoil was the oil of choice. Sparkplugs also changed from 100 to 200. I think if you were flying 30-40 hours a month then the 100 hour time would be OK, but if you are somewhere around the 10 to 15 hour a month range then I would do it at 50. This was also stated in one of the Ritax classes I took. I do 50 hour changes and also recomend that for most of my customers based on how they operate.

[FlyingMonkey]

I bet few 100LL guys change their oil every 25 hours - thats a really high cost if you dont do it, and a lot of work and still $60 bucks if you do it

 

I am a mogas guy, and I am changing 40 hours at worst case, three oil changes so far on 74 hours. Have the oil and filter for the next change I am gonna do at 90 hours.

 

So...four oil changes in 90hrs, average 22.5hrs per change, or less than half the recommended interval? That seems too often, let me give you my reasons why:

 

1) Maintenance Induced Failures (MIF). The more often things are touched/moved/changed, the more opportunity there is for things to be done incorrectly. A missed safety wire under- or over-torqued nut...a mistake, even on something as simple as an oil change, can cause catastrophic failures. Doing things more often than recommended probably won't reduce wear significantly (after all, the recommendations exist to help ensure an engine reaches TBO, so is more really needed?), but certainly will increase the risk of MIF.

 

2) You might *miss* some wear. For example, if there is metal collecting on the magnetic plug, it might not be enough to be alarming at 22 hours, but by 50 hours it could be a noticeable concern. Some problems develop slowly enough and you need to give the engine time to reveal them to you. By cutting service time by more than half, there might not be enough time between services wiping away the evidence to reveal a problem.

 

Do you plan to do a complete annual at 6 months? Rotax service at 50 hours? If not, why not? Why treat oil changes differently? If more is better, wouldn't changing oil before each flight be ideal? The service intervals are set where they are for reasons that balance need for inspection and safety with time in service for the aircraft. It's good to be proactive and on top of all your maintenance, but that can be self-defeating if overdone.

 

Just my opinion, it's worth exactly what you paid for it.

[FlyingMonkey]

What labs do ya'll use for oil analysis? Do you have to send for a kit, or how does that all work?

[Roger Lee]

I use Avlabs because of their huge database. That's an important part. The kit is a GA001. It's about $20 which includes pre-paid postage back to them. They will email your results in about 1-2 weeks. Always catch the oil sample in mid drain of the total volume. You don't want the first oil out as it will be heavy with contaminates and you don't want the last oil out as it is light in contaminates.

[FlyingMonkey]

The first oil change was at the FD recommende 20 hours. the other two were about 20 apart also. the next one will be at 40 hours. one of them had to be done because the A&P used a non rotax filter and it had to be changed out sooner than later.

 

Oh right, I remember your post about that filter issue. I think 40-50 hours is about the right interval. I'm at about 156hrs now, and have a change due at 177hrs. I might also have one done at my Rotax maintenance due at 202hrs if it's not a normal part of the Rotax service, so that one will be short at maybe 25 hours.

[Rich]

Andy,

 

I use AvLabs also. I guess Roger is paying the $20 per sample. I paid the $119 up front for the four samples and one filter analysis.

[Doug G.]

Hi Doug,

 

You can't tell how well an oil is working or how it's chemical properties are holding up just by looks. Blackened oil is nothing more than oil doing its job. Removing impurities and the black comes from carbon. There is no way for any of us to tell on the oil's break down based solely on color. The only way to really tell about the oil's worth is have have it tested. The City of Tucson tried that. Test all oil and change it based on the results of the oil break down. They found out it was far cheaper to just change the oil on a schedule.

I am assuming that Rotax has done that. Especially since I am using Sport+4 which they claim to have tested and recommend 100 hours on. I am erring on the conservative side by changing it earlier. At 50 it still looks very clean, at 70 not so much. So, I split the difference. I realize the reason is not scientific, but the only real number out there that is not an opinion is 100 hrs., right?

[Anticept]

I use Avlabs because of their huge database. That's an important part. The kit is a GA001. It's about $20 which includes pre-paid postage back to them. They will email your results in about 1-2 weeks. Always catch the oil sample in mid drain of the total volume. You don't want the first oil out as it will be heavy with contaminates and you don't want the last oil out as it is light in contaminates.

 

That's odd, airline SOAP labs usually they want the stuff that first comes out, and has a second container to capture a little bit more for comparison. You should probably ask the lab how they want the oil sampled.

 

As for oil change frequency: We change at 50 hours. Since we are a flight training organization, it gets very heavy on the abuse, and frequent oil changes are one of the best engine preservatives that we have

[FastEddieB]

What Roger put forth is what the AvLabs instructions say.

[Roger Lee]

I buy the kits by the case. Usually a dozen at a time. There is a break at those numbers. I have talked to Avlabs several times. Very nice and informative. Catch the sample in the middle of the drain. 50 hrs. is what is taught in Rotax schools. The manuals are not always up to date and are actually wrong in some areas. it's a slow process and things change from year to year which sometimes makes a manual revision and sometimes it doesn't.

[Anticept]

Thanks roger!

[Dan Kent]

I use Blackstone, because I started with them with my cars. They said they have a 912 database also, but don't know how extensive it is. Very responsive outfit.

 

http://www.blackstone-labs.com/