Freaky clean oil

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painless

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Feb 15, 2009
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Peshtigo, WI
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Jeff Orear
I have a long in the tooth O320 E2D with 1900 hrs SMOH that is running like a champ. All compressions mid 70’s or better, 71 psi in cruise, 54 at idle. Uses a quart of oil ever 6-7 hrs.

Up until now, after a few hours, less than 5 shall we say, the oil would start to darken. Nothing major, just slightly darker. Read that normal. But now, after that same amount of time, it’s looking like fresh oil. What the…?

Things that are different since last oil change. New oil lines to the cooler. The Phillips XC 20 W50 is coming in jugs with a new logo design.

I’ve noticed that the level is down the normal amount. Oil temps and pressure are normal. I know the cooler is working due to a louver mounted on it that is regulating temps.

Has my engine found the fountain of youth, or do I have big trouble?
 
Have you always used X/C? If you’re used to other oil’s rate of discoloration you’ll find X/C stays cleaner for longer. You’ll also notice less drool from the breather.
 
Discoloration is mostly from blow-by. Less is better. Keep doing what you’re doing.
 
If you're worried that the oil isn't darkening because it isn't circulating, your pressure and temps disprove that. Oil is a coolant, so if it wasn't circulating, your temperatures would be high.

I agree - keep doing what you're doing. Send oil samples out for analysis and make sure you have those trends. Otherwise keep on flying it.
 
I find my oil (just garden-variety Aeroshell 15W50) stays clean for a lot more flight hours when I'm tooling around locally at 55–65% power than when I'm flying long cross countries at 75% power.
 
Good thread. I've often wondered why my oil isn't black like all the others I drain at oil change. I've got at least 10 hours since my oil change and its still the same color as it left the container. I use Phillips Victory 100AW.
 
Timbeck2 said:
Good thread. I've often wondered why my oil isn't black like all the others I drain at oil change. I've got at least 10 hours since my oil change and its still the same color as it left the container. I use Phillips Victory 100AW.
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I'm at 9 hours air time since my last oil change, and the 15W50 on the dipstick also looks like it just came out of the can. I haven't needed to add any new oil yet (still at 6 qt, down from 7 at the oil change), so it's not just a bit of clean oil stuck in the filler neck. As I mentioned, I've been doing mostly lower-power local flights during the pandemic rather than higher-power long cross-countries, and I wonder if that has something to do with it. My oil seems to turn black faster when the engine's running all-out at 75% power for 3–4 hours at a stretch.
 
I switched from Aeroshell to Cross Country about three years ago in both planes and it seemed to stay clean longer, but it also looks lighter out of the can than Aeroshell.
 
MBDiagMan said:
I switched from Aeroshell to Cross Country about three years ago in both planes and it seemed to stay clean longer, but it also looks lighter out of the can than Aeroshell.
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I added Camguard to my 15W50 for the first time this year. It's far too soon to know if it's helping, but with a couple of 6-week flying pauses (for the voluntary stay-at-home requests), I'm glad it was in there for extra protection.

I don't really feel any strong attachment to oil brands. I kept using 15W50 because that's what the previous owner had been using 19 years ago; I was brand new to ownership, so if they'd been using Phillips, I probably would have stuck with that instead. It doesn't seem to matter much for a simple four-banger, as long as you fly regularly and do your oil changes.
 
Yes, for the most part, if you’re using a premium oil, the brand name on the can is not a big deal.
 
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