O-300D Oil Change Questions

PilotRPI

PilotRPI

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PilotRPI
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Coming up on my first oil change. Is the correct interval 25-30 hours? I have a screw on filter. Also, is that hobbs or tach time?

Does anyone here use CamGuard on their Conti O-300?

Thanks!
 
PilotRPI said:
Coming up on my first oil change. Is the correct interval 25-30 hours? I have a screw on filter. Also, is that hobbs or tach time?

Does anyone here use CamGuard on their Conti O-300?

Thanks!
Click to expand...
If you have a filter and not the original screen, you should be good to go to 50 hrs between changes unless there is an AD that require's it earlier. I have an O-300 A.

I use CamGuard in the IO-470s. I've never tried it in the -300, nor to I use MMO.
 
With the filter I used to go 35 -40 hours,I used Shell 15/50 that has the cam guard in the formula.
 
After 30 hrs my oil instantly turns ugly* so I know it's time.
*dark, more watery, smelly. Spin on filter.
 
We didn't have the filter on ours, so I changed at 25 hours. The oil was usually getting pretty black by then.
 
Even when you have a spin on filter you should stay at 25 hours, and no Cam Guard in the 0-300. You are simply over dosing the engine with a product it does not need.
20W50 Phillips at 25 hours, I have 4 customers that are now over 3000 hours on their lower ends with no lost in oil pressure.

the 0-300 is a water maker, it will settle to the bottom of the oil sump and stay there, causing this.
 

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a better picture of the corrosion damage of the oil sumps on a 0-300
 

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Tom-D said:
the 0-300 is a water maker, it will settle to the bottom of the oil sump and stay there, causing this.
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What makes it a water maker? Seems like the O-300s run hotter than many similar engines. I would think that they would be less prone to have water collect unlike my W 670 where the oil temp barely gets above 150F.
 
Camguard is a good product, regardless of what those who call it "snake oil" say. The proof is in the testing...not in SGOTI's B.S. And using multi weight w/o camguard is the worst thing you can do because multi weight oils leave parts exposed quicker than straight weights. They're okay if using camguard also, but I'd never run Phillips multi w/o it.

With an oil filter you "could" go 50 hours but...something that I didn't see mentioned yet...I also change my oil every four months regardless of time on it.

I used to fly a lot and I'd go 50 hours. But I'd get there in a month or two. Now that I only fly recreationally, like most others, I typically have 30 to 35 hours on my oil at fours months and I change it. More often definitely won't hurt things, especially if your oil doesn't get hot each time you fly, but my O-300 never had that problem. Keeping it cool was the problem.
 
bnt83 said:
Burning gasoline = exhaust gases + water :dunno:
Click to expand...

I believe his point was that O-300s don't have oil coolers and the oil tends to run hot (and burn off more combustion water). So why are they water producers? i.e. produce more water than any other engine.

There may indeed be a reason that they do but, like Fearless, my first suspicion would be that they would generally have less oil in the sump as a result of running higher oil temps than a "normal" engine.
 
timwinters said:
There may indeed be a reason that they do but, like Fearless, my first suspicion would be that they would generally have less oil in the sump as a result of running higher oil temps than a "normal" engine.
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Tim, see above. Did you mean "water"?
 
Fearless Tower said:
What makes it a water maker? Seems like the O-300s run hotter than many similar engines. I would think that they would be less prone to have water collect unlike my W 670 where the oil temp barely gets above 150F.
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They do not run hotter.

The 172 / 0-300 has a opening in the cowl in front of the oil sump which cools the forward sump compartment, which then acts as a condenser, plus the fact that the early 172 sets in a nose down position and the oil/water does not totally drain out of the front sump.
Add to all this.
The sump is magnesium which corrodes quickly.
Water is heavier than oil, so it sets on the magnesium.
The oil pump pick up is at the most rearward position of the sump.
This engine was designed at a time when all oil is a single weight, non "D" oil, Continental wanted the sludge to settle to the bottom and stay there, the water does too.
 
The oil temp seems to climb right up when flying, so that isn't an issue. It has the spin on filter adapter. But maybe I'll just change it at 30 hours anyway. It probably won't look too nice at that point.

Knock on wood, after 17 hours, I'm finally at the point where I should put a quart in. Only filling it to 7 qts. It went from 8-7 really fast, then took the rest of the time to get to 6, as it seems to just blow it out the breather.
 
timwinters said:
I believe his point was that O-300s don't have oil coolers and the oil tends to run hot (and burn off more combustion water). So why are they water producers? i.e. produce more water than any other engine.

There may indeed be a reason that they do but, like Fearless, my first suspicion would be that they would generally have less oil in the sump as a result of running higher oil temps than a "normal" engine.
Click to expand...

The operators I see run 7-8 qts. and the oil temps run well below 200 degrees.

I often see 1/2" to 3/4" of sludge in the bottom of the sump when I tear them down.

This sump in the 170/172 has a baffle that runs along all three sides of the sump back to the air passage for the intake system. this cools the oil very well in the front sump.
 
PilotRPI said:
The oil temp seems to climb right up when flying, so that isn't an issue. It has the spin on filter adapter. But maybe I'll just change it at 30 hours anyway. It probably won't look too nice at that point.

Knock on wood, after 17 hours, I'm finally at the point where I should put a quart in. Only filling it to 7 qts. It went from 8-7 really fast, then took the rest of the time to get to 6, as it seems to just blow it out the breather.
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are you certain you have the proper dip stick.. check to see what it shows when you first add 8qt. There 4 versions of that dip stick. and it is a Cessna part number for your aircraft.
Many engines have the wrong dip stick, and when filled to the 8qt mark will throw the top qt.
 
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Good to know. I'll check the dipstick. Everyone I know with a O-300 says it just tosses that top quart. Is it possible everyone is using the wrong one? Once it got to 7, it was a very very slow an steady usage. Hoping it stays that way.

My oil temp gauge just shows a green and red line. No numbers. When it starts creeping toward the red, I just take action to cool it off.
 
Tom-D said:
The operators I see run 7-8 qts. and the oil temps run well below 200 degrees.
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How do you run 8 quarts in an O-300? I liked to keep mine at 7. Myself and everyone I talked to on the 170 board have found that if you fill it to 8 quarts the last quart immediately gets blown out the breather.

When I was flying my 170 in the Southwest, I never saw the oil temp below 200F in flight.
 
Fearless Tower said:
When I was flying my 170 in the Southwest, I never saw the oil temp below 200F in flight.
Click to expand...

Do you have both blast tubes in place?

front sump will run 100 degrees cooler than the rear, IAW my IR thermometer.
 
PilotRPI said:
Good to know. I'll check the dipstick. Everyone I know with a O-300 says it just tosses that top quart. Is it possible everyone is using the wrong one? Once it got to 7, it was a very very slow an steady usage. Hoping it stays that way.
Click to expand...

Every one I know with a 170 when they do the 8 qt fill, the dip stick shows about 6.5-7 qts.

And the P/Ns are correct IAW Cessna.
 
When your engine runs hot,,,, all the more reason to change oil early. (25 hours)
 
Tom-D said:
Do you have both blast tubes in place?

front sump will run 100 degrees cooler than the rear, IAW my IR thermometer.
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Yes, blast tubes were there. Temp bulb IIRC, was right at the back bottom of the sump.
 
Fearless Tower said:
Yes, blast tubes were there. Temp bulb IIRC, was right at the back bottom of the sump.
Click to expand...

that is where the OEM installation was, the spin on filter has them in the end of the adaptor. much better, runs cooler.
He has the spin on.
 
Fearless Tower said:
When I was flying my 170 in the Southwest, I never saw the oil temp below 200F in flight.
Click to expand...

I hear you...regardless of the location...if it wasn't winter...and when I actually went somewhere in my 172...instead of just putzing around the area at low altitude...and got up to "real" cruising altitudes...7,000'...8,000'...9,000'...my temps would also be well above 200dF in flight...most of the time closer to redline (225). Because of the thin air presumably.

And, yes, everything on my 172 was intact also(tubes, baffling, me, etc.).
 
Fearless Tower said:
Is your redline at 225F or 240F?
Click to expand...

How do I tell if there are no numbers on the gauge? I just keep the needle well away from the red line.

I realized that I should have the correct dipstick. I did an oil change when I first bought it, put 8 qts in, and it showed 8, then quickly down to 7. Similar to everything I've seen on the 170 forum.
 
PilotRPI said:
How do I tell if there are no numbers on the gauge? I just keep the needle well away from the red line.

I realized that I should have the correct dipstick. I did an oil change when I first bought it, put 8 qts in, and it showed 8, then quickly down to 7. Similar to everything I've seen on the 170 forum.
Click to expand...
You can interpolate/estimate. The original gauges were marked with the red line at 225F. With modern oil, you can operate up to 240F. The reference is over on the 170 Association site.
 
You guys are totally correct. Took a closer look and in little print the gauge says 100 to 225. Never noticed that before. Was always just concerned about keeping it off that red line. Thank you!
 
So if I do 25-30 hours per oil change, I assume that is tach time? There is a fair bit of difference for me between tach and hobbs time. Is anything except for flight logbook measured using hobbs?
 
DutchessFlier said:
Shell 15/50 does not have camguard in the formulation.
Click to expand...

But it does have the Lycoming Snake oil that is not recommended for any engine with a friction clutch assemblies, such as the 0-300 / 0-200 and many other engines starters.
 
My Swift's O-300A will blow out an 8th quart so I always run it at 7. Fortunately, it has an oil cooler so my temps typically ran no higher than 190°.


Sent from my iPhone
 
I'm lucky if I can keep my oil level at 6.5 qts and she's the driest she's ever been now with @1600 hrs on the motor. I don't have the guts to do it, but I bet it would stop using oil around 5.5 or so on the stick.
 
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