What is your oil change interval?

texasclouds said:
Hobbs is for the pilot logs, tach for maint…right?
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Does not matter as long as you are consistent. The FAR requires a Tach but not a Hobbs.

Your method is sensible because it maximizes pilot time and minimizes maintenance cost. Owners of rentals prefer it for that reason. But if you fly your own aircraft and do your own oil changes, the difference is negligible, and you might prefer to maintain on Hobbs hours to do things sooner.
 
schmookeeg said:
I want to check more often for part numbers in the filter as I pass TBO
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:rofl:

If an engine burns 1qt every 8 hours or so, you're pretty much replenishing the oil and additive package on the go, right? No need to drain the oil. As the big boys call it, on-condition maintenance.
Replace the filter when the oil pressure suddenly increases, usually a good sign that the bypass valve has opened.
 
AV8R_87 said:
:rofl:

If an engine burns 1qt every 8 hours or so, you're pretty much replenishing the oil and additive package on the go, right? No need to drain the oil. As the big boys call it, on-condition maintenance.
Replace the filter when the oil pressure suddenly increases, usually a good sign that the bypass valve has opened.
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Hmmmmm that sounds straight out of the maintenance nightmares handbook :D My engines have shown poor proclivity to burn carbon, soot, or other particulates.
 
schmookeeg said:
... rationale being I want to check more often for part numbers in the filter as I pass TBO.
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Anything big enough to have a part # will probably in the screen, not the filter. The screen is harder to access and I suspect more often ignored during oil changes.
 
MRC01 said:
Anything big enough to have a part # will probably in the screen, not the filter. The screen is harder to access and I suspect more often ignored during oil changes.
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Lycoming jokes part of their overhaul procedure is removing the factory-installed screen gasket.
 
Kiddo's Driver said:
The recommendation was written by someone who is likely deceased now due to old age. It was written when oils were not what they are now. No one has ever updated the recommendation.
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Existing Airplane oils haven’t changed much in the last 30-40 years. Unlike auto oils which have continuously improved, airplane oils are stuck with chemistry that does cause them to become acidic faster than auto “detergent oil”.

With modern additive package and base oil technology we could easily have at least a 10w-50 synthetic if not 5w-50 synthetic (group iii) that works well with lead and air cooling now despite the failure of Mobil AV-1. The oil companies are likely making a healthy profit on what they make now (conventional or or in the case of A/S 15w-50 synthetic blend). With 100LL being sunset they sadly have no reason to innovate or take on the liability of doing so. If Exxon Mobil hadn’t cheaped out their AV-1 additive package that caused it not to deal adequately with lead salts maybe we could’ve continued moving forward, but I think the liability fallout froze the technology at about 1990.

The same goes for oil filters. Makes no sense that we pay 5x more for filters than filter 20 micron particles about half as efficently as a car filter. There is little to know flow penalty for 99% efficiency at 20 microns, yet we pay $50 for a champion that does 40%. It’s all liability and barriers to entry, and healthy profits in the existing product with no motivation to innovate.
 
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Domenick said:
I also run CamGuard with Phillips XC 20W50.

Juicing oil with CamGuard:
- 1.6 ounce/quart is 47.4ml Camguard per quart of oil.
- Each 16 oz bottle of CamGuard will treat 10 quarts of oil.

When I get a new case of Phillips X/C 20W50 oil, I pretreat each quart with CamGuard. Open the quart bottle and use a needleless 50 ml syringe to squirt the CamGuard into the bottle neck, reseal, and mark each treated bottle with a black felt-pen 'C'. That way I never need to think about it and the few quarts of oil I carry in the plane are ready to drink. And it's not rocket science, 45-50ml is fine.
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That’s a great idea!

Do you use 20w50 all year round?
 
If I know my plane will be idle I change the oil regardless of hours, otherwise 50 hours is my maximum, usually it’s less, if I figure I will have 70 hours on the oil at annual time, I will change the oil at 35 hours, but skip the filter change.
 
large bore connie turbo (TSIO-550)

Oil 25hrs
Filter alternate oil changes (ie 50hrs)
(Camguard)

I'm liking the visual effect at least:
When I was using longer intervals, the oil would be dark and obviously less viscous.
Last night I noticed it was very clean coming out of the drain tube; much less dark - and was not sheeting off the tube exterior but slow drips, more like new oil.
 
When I was in high school and afterwards I owned a 1964 Plymouth fury with a 318 poly. After changing the oil it would go 1200 mi and use one quart, then it would go 800 mi and use the second quart. That told me as the oil aged in the engine it was being degraded, so I started changing the oil when it was ready for the second quart at 2,000 miles.

I believe aviation oil does the same thing, degrades as time builds up on the oil in the crankcase. I changed my oil at about 25 hours, but I don't change the filter until 50. Only usually run 50 hours a year so my AI does the oil change during annual and changes the filter. I did that on my '68 piper Cherokee with 0320 and I do it on my 64 Mooney, that does not have an oil filter only a screen. Mooney recommends replacing the oil at 25 hours if there's no oil filter. I think that is sound advice with or without an oil filter.
 
Narwhal said:
Existing Airplane oils haven’t changed much in the last 30-40 years. Unlike auto oils which have continuously improved, airplane oils are stuck with chemistry that does cause them to become acidic faster than auto “detergent oil”. ...
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Blackstone's opinion and data on oil acidity:
https://www.dropbox.com/scl/fi/dd62...port.pdf?rlkey=o9es2w7mcvxcpwhexsveuzelu&dl=0

I use CamGuard because it lingers on metal parts longer than just oil, and here in the far-left, upper corner of the contiguous 48, winter comes with long horrid weather stretches.
Nikhiln25 said:
That’s a great idea!

Do you use 20w50 all year round?
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Yes.
 
Ok, let's blow this thing up.

Camguard with Aeroshell Plus?

I say no.
 
Ed Haywood said:
Ok, let's blow this thing up.

Camguard with Aeroshell Plus?

I say no.
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Plus has 16702 Lyc additive which is AD for -H2AD engine and often used in others. Camguard on top seems to be unnecessary even though the additives, while sort of in the same family, differ.

Anecdotally would not use either in Continentals with starter adapter (slipping) or small ones without (loss of prime when sitting).
 
A few years ago at AirVenture I spent some time talking with one of the older experienced engineers at Shell. He told me that there was a point of diminishing returns and then measurable additional wear that occurs if using too much additive. He recommended that if I use any AeroShell Plus to NOT add any Camguard.

I asked because I had just done this very thing. He said to finish out my oil change interval and that less than 50 hours was not enough to cause harm.

For what it’s worth…
 
Domenick said:
Blackstone's opinion and data on oil acidity:
https://www.dropbox.com/scl/fi/dd62...port.pdf?rlkey=o9es2w7mcvxcpwhexsveuzelu&dl=0

I use CamGuard because it lingers on metal parts longer than just oil, and here in the far-left, upper corner of the contiguous 48, winter comes with long horrid weather stretches.

Yes.
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I would counter that article with this one: Ed Kollin Brevard Response

If the premise is that we can ignore the 4 month oil change recommendation because overbased “modern oils” (automotive) can, I think Ed explains why that might not be true. The TAN value blackstone tracks isn’t actually a good indicator for corrosion, as Ed discusses:

Ed Kollin said:
It's apparent that Mr. Brevard shares the same skepticism that I had while working at Exxon research as the director of the engine laboratory in the Advanced Fuels and Lubes group for almost 15 years. I have probably tested over 100 fuel and lubricant additives and can honestly say that I've never tested one that actually did all that it was claimed to do.

Unfortunately, I have to take issue with Mr. Brevard's methods and assumptions as he proceeded to test Camguard. I particularly take exception to his which one is it where he states, “ Independent testing from Mike Busch’s camp as well as empirical analysis from relatively long-time users, show a trend downward in wear metals, particularly iron, and a correlation between corrosion-induced wear and CamGuard’s reported success in reduction of engine oxidation.” Yet in the next breath states, “The data supporting the claim are weak. Wear metals can be seasonally responsive and, frankly, Busch’s 2’700 hour engines “on their way to a 3000 hour TBO”, should be considered “outside reliable data.”

Independent oil analysis data over the last 10 years show an average reduction in wear metals, iron, nickel, and chrome, an average of 35% when using Camguard. Also for the first time ever, when Mike Busch tried Camguard he experienced a reduction in iron, from rust, while his airplane was sitting for long periods during its annual inspection.

How is this outside reliable data?

Mr Brevard incorrectly begins this analysis from the perspective of an automotive oil and not that of an ashless piston aviation oil. Only two of the elements, phosphorus and calcium, contained in three of the 11 ingredients in Camguard, even show up in his inductively coupled plasma elemental analysis. His reporting and subsequent conjecture about the sodium, molybdenum, magnesium, boron and zinc found in his analysis as
working elements in Camguard is incorrect and misleading. They are trace elements in the various additives that we used to formulate Camguard and not active in the formulation.

Mr. Brevard goes on to talk about the acids that enter the crankcase from blow-by as the cause of the corrosion and thus a major issue concerning longevity. While not technically correct (blow-by puts partially reacted fuel and free radicals into the oil that lead to organic acid formation) the effect is the same and it is blow-by that causes all the problems. In one paragraph, he mentions that reducing wear in and of itself is not much of a concern for the life of the engine. Then two paragraphs later, talks about worn engines putting significantly more blow by contamination (acids) into the oil.

Mr Brevard talks a lot about the buildup of acids and how they are reflected by an increase in the Total Acid Number or TAN. He states, “Total Acid Number (TAN) does increase with engine hours, and every tested producer of engine oil does a good job of controlling the increase whether CamGuard is used or not”. The Total Base Number (TBN) is the capacity to neutralize acid build up in motor oil. Again, Mr. Brevard confuses automotive oils containing metallic overbased detergents and a TBN of 7 with an ashless aviation oil with a TBN of 0, or ZERO acid neutralization!

Kristen Huff at Blackstone Laboratories measured the TAN and TBN of new Aeroshell W65 and used Phillips 20W-50 oils. The TBN of the new W65 was 0 and the TAN was 0.2. As expected, the TBN of the used Phillips oils 25 hours and 50 hours was essentially 0, but the TAN increased very slowly at one point per 25 hours of use (1.2 TAN at 25 hours and 2.1 TAN at 50 hours). The fact that the TAN increases at all is because aviation oils do not have any acid neutralizing capacity!

Camguard’s antioxidants prevents free radical oxidation and it also prevents the further oxidation and polymerization of the partially reacted blow-by fuel thus preventing deposits and formation of organic acids. The results speak for themselves

(See web links below). Mr. Brevard also alludes to the fact that Camguard has no effect on the increasing TAN. Another thing he did not realize was that Camguard contributes greatly to the TAN, which would distort and invalidate his findings.

FAA certification engine results:

www.aslcamguard.com

Engine Oil Licensing and Certification Data | Camguard

Access Camguard's detailed Engine Oil Licensing and Certification Data for assured quality and compliance. Essential for informed decisions in engine maintenance.
www.aslcamguard.com www.aslcamguard.com

Oxidation and deposit testing of Camguard:



Probably the most important aspect that Mr. Brevard never discusses is a quantity of water entering the crankcase with the blow-by fuel. It is water that is acidified by the small amount of organic acids that lead to the corrosion problem and any discussion about TAN and TBN is meaningless. This is because Camguard contains an extremely effective ferrous metal corrosion (rust) inhibitor. The inhibitor is a self assembling type that forms a continuous monolayer on the steel surfaces every time the engine stopped.

The inhibitor film prevents water and acids from reaching the surface to cause corrosion. We have tested Camguard in the presence of hydrochloric acid, much stronger than the organic acids found in used aircraft oil.


Then Mr. Brevard goes on to talk about zinc, phosphorus, flat tappet camshafts and lifters and how older car engines are so similar to aircraft engines. But aircraft engine metallurgy is really quite different than any automotive technology. He mentions that, “….the oil companies won’t disclose the levels of phosphorus and zinc in their aviation oils”. The problem is aviation oils cannot use zinc antiwear they utilize phosphate esters of varying activity and effectiveness. Once again, he confuses automotive technology and oils with that of aviation.

Mr. Brevard assumes that we use phosphorus from ZDDP (like auto oils) to form anti- wear films. While we do have a small amount of phosphorus (not from ZDDP) for both anti-wear and anti-stuff protection, we have four other ashless additives that provide us with superior anti-wear and anti-scuff over a very wide temperature range. In a comparative test, this combination of anti-wear additives provides approximately twice the protection of ZDDP (zinc), anti-wear found in automotive oils.

While I appreciate the effort Mr. Brevard has put into “analyzing” the effectiveness of Camguard. I could've saved him a lot of time and effort if he would have contacted me to discuss all of this. In fact, I probably would’ve told him much of what’s in it and how the chemistry works.
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So maybe what I said about oil becoming acidic could be more correctly stated as: airplane ashless dispersant won’t neutralize acid build up as well as auto oils.
 
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Are there any conflicts of interest from any of the authors in the above? If one has a motivation to bash or defend a product, then some of writing comes with the feeling of bias, regardless of if there is any. Hard to know what to believe unless someone shows the data and allows the reader to draw their own conclusions as well (like a professional or academic paper). Blackstone clearly showed the data they used. Now sure, there could be fraud or error, but I don’t think Blackstone has a dog in the fight (could be wrong).
 
I recently started following Continental’s MO for straining the drained oil with a 1,200 micron screen. Figured it’d be a total mess. To my surprise it’s going rather smoothly. Also makes for a nice area to drain oil filters. The strainer sits right on top of a 5 gal bucket. Maybe I should charge a little more for oil changes now..hehe
 
asicer said:
But they also recommend every 4 months
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pedro-monkey-puppet.gif
 
Jdm said:
I recently started following Continental’s MO for straining the drained oil with a 1,200 micron screen. Figured it’d be a total mess. To my surprise it’s going rather smoothly. Also makes for a nice area to drain oil filters. The strainer sits right on top of a 5 gal bucket. Maybe I should charge a little more for oil changes now..hehe
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For those micron impaired ...
1200 microns = 1.2 mm = 0.047"
 
Jdm said:
I recently started following Continental’s MO for straining the drained oil with a 1,200 micron screen. Figured it’d be a total mess. To my surprise it’s going rather smoothly. Also makes for a nice area to drain oil filters. The strainer sits right on top of a 5 gal bucket. Maybe I should charge a little more for oil changes now..hehe
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Domenick said:
For those micron impaired ...
1200 microns = 1.2 mm = 0.047"
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At that size, the screen had better be clean... :oops: I always find some debris in the oil filter pleats, but it is dust-size - nowhere near those dimensions!

For comparison, Lycoming SB480F defines 3 sizes:
"Large": Chunks are > 3/16" in size (4x bigger than 1200 microns)
"Medium": Chips are smaller than chunks
"Small": Dust

Lycoming says chunks and chips require further analysis, but dust is fine so long as there's not too much of it. So anything caught by a 1200 micron screen would be "chunks" or chips" and require analysis.
 
Sorry fellas. It’s not 1,200. I shouldn’t have gone by memory. The continental MO states: a 1,000 micron or less (approximately 0.040” or less) mesh screen to strain the oil sump contents.
Still rather large. I will say, the two engines I found making metal would have been obvious by straining.
 
The screen system I’m using has two sizes of stainless mesh that can both be used together if desired. The larger is well over the 1,000 micron. I’m only using the smaller 650 micron option. Hot oil flows through 650 quickly enough not to pool up on its way into the 5 gal bucket.
 
MRC01 said:
Interesting take on acidity. I noticed that "XC" (Philips 20w50) is over-represented in the healthy (non-acidic) oils, and under-represented in the unhealthy acidic ones.
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I noticed that too. There were more than double the Aeroshell samples, so I ran the averages just to confirm.

Samples:
XC, 17 - Avg=1.03
Aeroshell, 40 - Avg=1.36
Exxon, 3 - Avg. 1.7

The things Blackstone said in the TAN section of that article did put my mind at ease somewhat, basically saying that it wasn't much of a concern, and given the fact that the virgin oil starts between .4 to .8, it seems any of those readings are minimal. But I won't be switching to Exxon lol.
 
I change my oil and filter every 25 hours (which with my flying schedule, works out to about every 4 months). That is convenient, since one of the changes is during the Annual. I also like having the cowlings off every 4 months to look over the engine and firewall-forward components real well.
 
The self-launcher I fly has a 2 liter fuel tank, a typical launch burns 0.5 to 0.8 liters (depending on several factors). We mix replacement oil and fuel in 0.5 liter containers. So, while it's all interchangible and new mixes with old, the oil at the end of a week or a weekend day is mostly, if not all new oil. :)
 
Nikhiln25 said:
My A&P (outside of nyc) is $150/hour of labor and charges 2 hours for oil change, and 3.5 if he’s going to do spark plugs as well. I’ve found a local A&P for my next oil change to do it with me so I can learn (mainly make sure I do safety wire properly.. I’ve watched videos online how to do it). Though I’m really not looking forward to taking my lower cowling off - putting that on alone is no fun
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Cowlings can be a PITA. We had a C55 Baron and it looked as simple as can be. Always required two people and extensive cursing.
 
Domenick said:
I also run CamGuard with Phillips XC 20W50.

Juicing oil with CamGuard:
- 1.6 ounce/quart is 47.4ml Camguard per quart of oil.
- Each 16 oz bottle of CamGuard will treat 10 quarts of oil.

When I get a new case of Phillips X/C 20W50 oil, I pretreat each quart with CamGuard. Open the quart bottle and use a needleless 50 ml syringe to squirt the CamGuard into the bottle neck, reseal, and mark each treated bottle with a black felt-pen 'C'. That way I never need to think about it and the few quarts of oil I carry in the plane are ready to drink. And it's not rocket science, 45-50ml is fine.
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I also run CamGuard and Phillips XC 20W-50.

What I do is open the CamGuard and use a syringe (one made for mearing two stroke oil) to pull off 1.6 ounces an put into one bottle of oil and repeat with a second bottle of oil. I also mark each bottle CG. I use these for topping off between changes.

My engine takes 8 quarts, so the CamGuard with 3.2 ounces gone is perfect. And less measuring that doing every bottle of oil.

I shoot for 30 hours for oil change, but I am turbocharged, so shorter change intervals.
 
I just spent many AMUs on an XP470 (P-Ponk) for my C182. Oil and filters are relatively inexpensive. I'm going to try to keep to a 25-hour oil change protocol.

YMMV
 
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