A long but interesting thread, worth revisiting; the problem is when we get to 10 pages, it’s hard to extract the info…
What I get from it:
- Camguard is ok to use in turbocharged engines as well
- it’s better to use it with straight mineral oils, W80 in winter, W100 in summer; you can mix these with AS 15W50; but using Camguard with “pure” 15W50 is not recommended (is that correct)?
- oil analysis done with the usual European labs has a low signal to noise ratio, Blackstone in the US is much better
Now time for a dumb question: we all accept we need to run our pistons weekly or at least biweekly to prevent corrosion; we also seem to accept that’s because the oil film that covers our engines “slips down” with time and leaves the metal exposed. I fly a type (PA46 Lyco) which is famous for spilling on its belly 2 quarts of oil after each oil change. I can tell you for a fact that this oil film stays in place for a very long time. Why would that be the case, while the oil film covering the camshaft slips away?
Those are fair questions. The oil coating on my milling machine and lathe at home does protect the slides from corrosion for months.
But that is at room temp and thus a much elevated temp-DP spread i.e. a RH figure which is way below the 99-100% you get outside in the rain, or in a non-heated hangar with lots of holes.
For example, with
EGKK 181220Z 23017G27KT 9999 FEW013 BKN020 13/11 Q1004
the 13/11 spread gives, with an online calculator, an 87% RH.
In the house, say +21C, it drops to 53% RH.
Even in a hangar which gets a tiny bit of solar heating, say to +15C, the RH is 77%.
There is a huge amount of evidence that not flying for some number of weeks is likely to generate rust, and this then trashes the interface between the camshaft and the cam followers.
What nobody can enumerate is what conditions are needed for a given speed of rust formation, inside the engine.
One pilot I know suffered a massively corrosion-damaged engine (camshaft etc disintegration) after a regime where there were gaps of maybe 5 weeks between flights, and he was able to vouch for that all the way back to an engine rebuild. Lab tests found the metal was perfect, eliminating the “Lyco crap metal” argument. I am trying to get him to go public with the results… Camguard was not used in that case. So it looks like a few weeks can get things rusting nicely 
That is perhaps the most rapid example, and it will get better from there, according to the hangar situation, the wx (Arizona versus Shoreham Beach) etc.
Another thing is that the crankcase is full of hot corrosive vapours, post-landing. It seems possible, and some anecdotal evidence might support this, that if you built an engine fresh, oiled everything inside as you go, and left it in a shed without ever running it, it would last a year before going rusty inside.
But some owners do just get lucky…
However i suspect the “luckiest” ones are the ones who don’t do oil analysis and whose maintenance company doesn’t cut open the oil filter 
The rest is all in the thread.
I fly a type (PA46 Lyco) which is famous for spilling on its belly 2 quarts of oil after each oil change
That’s incredible – where is it coming from?
I fly a type (PA46 Lyco) which is famous for spilling on its belly 2 quarts of oil after each oil change
Which means you put in too much oil. My engine has a 9qt sump and the POH mentions that you should fill in 9qt. I fill in 6qt because the difference is thrown overboard rather quickly. Find out which level of oil your engine is happy with and keep it there.
The POH says put in 12Q. After a couple of hours it goes down to 10.5Q and stays there, with oil seen on the belly as I mentioned. However how can I know if 1.5Q goes on the belly, or if it’s only 0.5Q and the other 1Q finds its way into some dark place in the engine where it’s needed? So I put in 12Q and clean the belly.
Peter, I am not disputing at all that rust formation is a massive threat to our engines when they go unused; I’m just wondering what the mechanism is that makes some part of the engine exposed, while I see how long oil can stay in place (even on parts of the plane which are exposed to airflow).
However how can I know if 1.5Q goes on the belly, or if it’s only 0.5Q and the other 1Q finds its way into some dark place in the engine where it’s needed? So I put in 12Q and clean the belly.
If the oil disappears into a “dark place” where it is needed, how would it have gotten out there for the oil change? Don’t fill too much oil into your engine, if it wants 10.5q, give it 10.5q. Especially when the piston rings leak a bit, the pistons tend to pressurize the crankshaft which makes it push out the oil through the breather tube. Not much to do against other than putting in less oil. The sump is calculated with the max allowable oil consumption per engine data sheet * aircraft endurance. When it’s your plane and you know it well, there’s no reason to be that conservative, especially since you lose the first quart in no time.
Also I do not share the common belief that lack of use (say a few weeks at a time) makes the engine rust. There is much more evidence for the opposite than for this hypothesis.
However how can I know if 1.5Q goes on the belly, or if it’s only 0.5Q and the other 1Q finds its way into some dark place in the engine where it’s needed?
I am very sure no IO540 variant can hold 12qts. Anything over 10 goes straight out of the breather. I fill to “9”.
The only “dark place” in an IO540 is the oil filter and that holds less than 1/5 of a quart (I know – I cut them open at home).
So after a service we put in 9qts plus about 3/4 of a camguard bottle (the other 1/4 of the CG bottle is used to pre-mix a few topup oil bottles I carry in the boot) and that takes it up to “9”, which drops just below “9” after the engine is run.
I am not disputing at all that rust formation is a massive threat to our engines when they go unused; I’m just wondering what the mechanism is that makes some part of the engine exposed, while I see how long oil can stay in place (even on parts of the plane which are exposed to airflow).
I would suggest the hostile environment, post-shutdown, inside the crankcase would be a good start. Also any flight under ~1hr in the air will fail to boil off the water. The oil temp is regulated way below +100C, and even allowing for the boiling point dropping at higher altitudes, it is clearly hard to remove the water. Whereas an external engine surface, post-landing, will see the RH close to zero, simply due to having heated up all the air around to something like +60C.
The airworthiness limitation oil burn for an IO540 is c. 1qt per hr, which would be a totally shagged engine, but you then have to fill to “12” if you want the plane to reach empty tanks before it reaches an empty sump Hence, I believe, the “12” recommendation. It’s for pilots who fly a shagged engine and don’t care.
Also I do not share the common belief that lack of use (say a few weeks at a time) makes the engine rust. There is much more evidence for the opposite than for this hypothesis.
I have never seen such evidence. Just compare the iron PPM values in the two Blackstone oil analyses posted a page or two back, and correlate them with the hours flown… Every time you take the p1ss out of my Nokia phone I will ask you to post your oil analysis
Denopa and Achimha
Have a look at http://www.eaavideo.org/video.aspx?v=1149666747001 This is a free Webinar of Mike Busch where he talks (for 2h.) about oil, additives etc. He says that an engine with 12Q. oil capacity should not be filled more than 9Q (I used to keep mine at 10Q) and that most engines die not due to being used but due to being underused, or in his words: “We do not wear our engines, we rust them”.
Camguard definitely works – I have years of oil analysis before/after to prove it.
Peter wrote:
Camguard definitely works – I have years of oil analysis before/after to prove it.
So what do your Oil Anaylsis reports tell you that leads you to believe that Camguard “works” ?
I can’t tell by the oil analysis but I use Camguard too (D100 oil + Camguard) and according to many US shops, pilots and mechanics Camguard really seems to prevent the engine from corroding inside, especially if you don’t fly too much, like in Euopean winters. I am normally not into homeopathy and somewhat of a fatalist, but I have a pretty good feeling about Camguard and will stay with it.
