Just read your story, it sent shivers down my spine; I had darned near the SAME thing happen to me. Except it was in a PA-12, and would have quit either on the beach or over swamp.
My first sign something was wrong was the oil temp. It was still in the green, but was running 20 degrees hotter than normal. When I landed the FRESH oil (less than 10 hours on it) was black as coal, and smelled burt. And I had consumed 2 quarts in 5 hours. I brought these concerns to my boss/shop manager. I was brushed off with "is it still in the green? Oil is less than 1 qt/hour?" And "they all get dirty quickly". I was inexperienced at the time, and easily intimidated; he'd been doing this for 59 years, I had been towing banners for 1 1/2 months.
Of course, I mentioned that the oil had NEVER gotten that dirty that fast, and had run much cooler when it was a lot hotter out, and the oil consumption had increased by 200% in a day. These seemed to me to be warning signs that a Very Bad Thing was about to happen. To placate me, the did a compression test: cyls 1-3 were 80/80, #4 was 70/80. All within tolerance. But 3 weeks a go they were ALL
80/80. Everything in MY
mind was screaming "SOMETHING IS
NOT RIGHT. IT IS
TEARING ITSELF APART" But every experienced mechanic and pilot I told about it told me the same thing "don't worry, it's all within tolerance. Stop being a baby and fly"
This went on for 3 weeks. I had more and more warnings, the oil pressure bypass stuck open, so I would get normal pressure at cruise, but I would lose almost all of it when the power was pulled back. Again "don't worry- see, it's working FINE now"
Finally, something DID let go. While under tow I started losing power. The engine was running real rough, and she was backfiring something fierce. I thought I finally blew the jug. I was finally able to get some power back when I leaned the mixture a bit and gave it more throttle. I was able to nurse it home, when it started doing it again after I dropped my banner.
I pulled her into the hanger, pulled the plugs and the ones on #4 were soaked in oil. The next day they pulled the oil screen- it was FILLED with aluminum shavings. I mean FILLED. We drained the oil- you could SEE
the metal flakes in it. Pulled the oil pan off, where we found the remains of one piston ring and bits of a piston pin. The pin had been rubbing against the cylinder wall, and wore a groove in the jug. Some how the oil ring had also come apart, this was probibly why my plugs fouled out.
I learned my lesson. Be skeptical. I may not be a professional mecahnic, but I have turned a few wrenches in my day. I have a passible knowlage of what is right and what isn't. There were all kinds of signs telling me that something was NOT right. I let people who's asses weren't on the line tell me not to worry about it, and it almost cost them an airplane, and me an NTSB report. Listen to your gut, and remember there are things other than gauges that will tell you if something's not right.
Glad it turned out ok for you.
And please, I'm not dissing all mechanics. This was more of a situation where the management wasn't taking the pilot seriously because we were just kids that didn't know any better and he had been doing this a lot longer than our parents had been around. After that, I began to take a more proactive role in the maintinace of my plane. It wasn't "can we fix this?" it was "this needs to get fixed, NOW" or, more often than not, I'd just fix it myself.