The bearings initially don’t seize, they simply don’t roll as smoothly. They feel ‘crunchy’ if you roll them by hand. By the time the bearings seize you’ve most likely wiped the lobe due to friction.
There are no bearings in the roller. It's a round wheel on a pin. The only antifriction stuff in there is the oil. Both those pieces are hardened so as to avoid galling each other.
EDIT: I just came across an article that suggested that there might be needle bearings in there. If so, I stand corrected. But the presence of needle bearings also means that moisture will destroy them, too. No ferrous part is completely immune to corrosion.
The roller lifters in my 1946 deHavilland Gipsy Major aircraft engine had no needle bearings. But then, those engines were lucky to make 1000 hours.
Most cams fail due to corrosion. Lycomings put the cams as far away from the oil as humanly possible. That means the protective oil coating will eventually dry up and allow corrosion. It’s the small initial pits that flake off and you find in your filter.
The oil will fall off a Continental cam, under the crank, as fast as it will off a Lycoming cam. The oil does not "dry up." It just runs off, and it does so very quickly when it's hot.
Cam and lifter corrosion is primarily due to moisture in the crankcase. People who run their engines without flying them are pumping their cases full of water. Then some of them have oil sump heaters that raise the vapor pressure of that water, driving into vapor that condenses on the stuff higher up in the engine, including the cam and lifters. The Lyc is worse that way. There is also condensation on the cylinder walls and everything else. We have found rust on magneto gears and accessory case gearing, too.
If people would only read the stuff the engine manufacturers publish, which tells them to avoid short runs, and don't ground-run it thinking you're helping it.
Letting any engine sit is simply bad for it. There is no way to coat internals other than by pressurizing the system and putting a fresh coat of oil on everything. On a car, the oil coating is gone after about 3 days. If there is a pre-oiler system I don’t know of one.
Pressurizing the system does not get oil on the cams or lifters faces or rollers. They are lubricated by oil thrown off the rotating crankshaft. Only the camshaft bearings and lifter bodies get pressure lubed. This is basic aircraft engine technology that is sorely misunderstood by way too many amateur experts.
And there ARE preoiler systems. You just don't know, as you admit.
https://www.oilamatic.com/
More info:
https://generalaviationnews.com/2019/07/01/why-arent-engine-pre-oilers-more-popular/
What you really want is some sort of electric pump to turn on once every day and mist the engine intervals and rotate the engine. I don’t think a certificated version of that exists.
See above. Certified. And see also my previous comments about it doing nothing for the lifter/cam interfaces. People buy stuff in ignorance and are amazed when they still have troubles that they thought the new doodad would fix.
