Too much of a good thing?

RyanB

RyanB

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As some of you know, the Archer was down for an extended period of time for repairs. Having just gotten it back, I’m curious how long CamGuard is good for. The mechanic changed the oil in it and added CamGuard around mid-August. It then sat pretty much dormant ever since, up until last week. I know the recommended oil change intervals are 4 months or 50hrs whatever comes up first, but what about CamGuard? Would the pint added in August still have an effect? If not, is it safe to add another before the oil gets changed?
 
RyanB said:
Elaborate? Seems like you’re in the minority.
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Known to cause low compression, sticking valves, stuck rings. I have never used it and never will.
I have seen engines that run it and the cylinders come off.
Marvel Mystery oil is the way to go if you want to use a oil or fuel additive.
A buddy just pulled 2 cylinders for low compression and took them to a very well known cylinder shop. He pulled them apart and said right away if you wouldn't have used Camguard you would still be flying.
 
Camguard is made for periods of inactivity. Better off using storage oil.

4 months is ridiculously short.

I don’t use camguard.

Opinion.
 
Only negative thing I've heard about camguard isn't really a negative, because I think it's on the label if I remember right, and it's not to use it during break in.
 
During our starter adapter repair I was asking about camguard and marvel mystery and was told that camguard might not be a good idea for the starter adapter. I don't recall the reason but next time I chat with the mechanic I will see what he meant.

We now use Marvel though.
 
If new oil was put in last Aug, then it sat in annual, I would fly it awhile before any oil change. I wouldn’t let the Camguard effect that decision, I wouldn’t add any more.

Better than Camguard or any other additives is routine flying. Can’t do much about an unexpected, extended annual. How long now?, 2-4 months or so.
 
Oh boy.

Don't sweat the oil. The time change recommendation is to account for two factors: oxidation and acidification. The oil will oxidize just sitting around, but honestly the amount of air moving through your crankcase is so small is not going to be that big of an issue. If your plane lived outside in equatorial Africa it might be an issue.

The other issue is that running the engine will produce acids... the water produced during combustion tends to be acidic. The oil absorbs and neutralizes this acid to some extent but it's capacity is limited. If you ran the engine 20 hours and then let it sit for months, you'd probably see some corrosion.

Fresh clean oil in there? Don't change it. It's fine. If it were mine, I'd start the clock when you first run it, then do 50hrs or 6 months.

The bigger issue with lycos is the oil dripping off the cam and it getting rusty. That is what camguard is for. It helps keep the thin film of protective oil stuck to the cam a bit longer. It also has friction reducing additives. I've never heard anyone say it causes any kind of harm, and I struggle to understand the supposed mechanism. The camguard won't time out, no need to add more or change it. It's just an additive package.

Marvel mystery oil is essentially mineral spirits, a tiny bit of oil, and a nice fragrance. It will thin your oil and make it run off the cam faster. Added to fuel it may help to clean and lubricate the carburetor and valves, but avgas is so clean to begin with and it's such a tiny amount of oil I have my doubts. I would never put it in the crankcase.
 
I agree with everything above except for one post.

Go fly your bird for 50 hours until next oil change. I would not add anymore cam guard until next oil change. Hopefully the engine was run after the last oil change before it sat during the annual to mix the cam guard.

I find it interesting, irritating, amazing, entertaining, amusing all the opinions folks have on motor oil and additives.
 
Sinistar said:
During our starter adapter repair I was asking about camguard and marvel mystery and was told that camguard might not be a good idea for the starter adapter. I don't recall the reason but next time I chat with the mechanic I will see what he meant.

We now use Marvel though.
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Both the small and large Continentals use friction-type overrunning clutches in their starter drives. They rely on the ability of the dogs or spring to clamp down on a smooth shaft in order to turn it to start the engine. Anti-scuffing additives such as those in Camguard (if they're actually there) and the Lycoming additive (definitely there) found in Aeroshell 15W50 can sometimes prevent that clutch from grabbing, allowing it to slip and the starter can't start the engine. Not always, not even often, but it happens.

This article claims that Camguard has no friction modifiers. https://cessnaowner.org/camguard/

Lots of opinions out there.
 
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Jim K said:
The other issue is that running the engine will produce acids... the water produced during combustion tends to be acidic. The oil absorbs and neutralizes this acid to some extent but it's capacity is limited. If you ran the engine 20 hours and then let it sit for months, you'd probably see some corrosion.
Click to expand...
Oil additives can counter acidity, but water mixed with oil in the presence of metals that catalyze the reactions will form acids. Lots of them. Various elements in the oil do it. Hydrochloric, sulfuric, and nitric acids I have seen listed as likely to be found in there. That's why ground-running the engine is so bad: it pumps moisture into the case but provides too little time and heat to drive it off again. Aircraft engines also don't have the PCV systems that cars use to get good crankcase scavenging; PCV requires manifold vacuum, and aircraft engines spend most of their time with nearly none of that.

On acid formation:
https://blog.aopa.org/aopa/2017/02/24/why-change-the-oil/

https://www.aviationconsumer.com/uncategorized/aircraft-engine-oil-changes-how-often/
 
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