
About 800 miles into a ride, engine was making a loud clattering at 70 mph, 20 miles from my son's house, where I was stopping. I pulled over to a McDonalds, let it cool, was still clattering. I took side roads at no more than 35 mph to his house. When I opened the oil drain plugs, oil poured out with little viscosity like it was water. I had made the mistake of changing using oil that apparently was at least 10 years old. Just in that 800 miles riding, oil apparently broke down from heat and turned really thin.
It splashed out of the oil drain pan like it was water, weird.

I put 3 quarts and 11 ounces of standard 10W40 motor oil in the bike, and 11 ounces of Lucas. Engine was now running quieter, clatter was completely gone. (This was before I learned from this forum that Rotella was a better oil to use.)
Rode close to 1,000 miles home back to New Mexico. Since then as of late, I've noticed on a few cold starts, the unusual tappet noise like one lifter wasn't fully filling with oil like it should, goes away after a rev with oil warm up and doesn't appear on the rest of the ride, unless we stop and bike rests and cools for a couple hours. (Sounds like the sticking lifters on our old 1964 Ford Falcon with 200 cubic inch in-line 6 with hydraulic lifters. I fixed that by removing the lifters, disassembling, degumming in volatile solvent soak, reassembling. That was in high school in the early 1970's.

I'm thinking of adding Seafoam or may be something a little stronger like STP fuel treatment to the oil. I suspect that somewhere in its previous past it may have not had the oil changes it should have had, and there is some oil spooge gumming inside the lifters.
I know this will raise the eyebrows of some, but for the past 10,000 miles, since that incident, I've been using Lucas Heavy Duty Oil Stabilizer in my oil changes. There used to be a recommendation on the back that stated it was great for Harley-Davidson and other motorcycles. Recommendation was 20% in motorcycles with dry clutches, 10% for wet clutches. Latest bottles no longer have motorcycle recommendations.
I was using it in my 1986 Suzuki LS650 Savage. One winter during several weeks of non-use, I removed the head cover on the air cooled engine to do some work. The entire overhead cam chamber was glistening as with a wet coating of oil like the engine was just run, so their statement about preventing damage from dry starts is true. I knew the difference from my opening the head cover previous to Lucas use. It was an eye opener.
Over time though, the Suzuki started developing a slipping clutch in 4th gear (top gear, bike's 4 speed was wide ratio, only 300 rpm difference in top gear compared with the later 5 speed). I discontinued the Lucas and after an oil change or two the slippage stopped. So, if any are having slippage problems and suspect their particular oil or additive, just letting you know that sometimes just going back to OEM oil recommendations can fix the slippage issue.

So far, haven't had any problems with the Lucas. Going back to my first question, has anybody been adding a solvent based fuel cleaner to their crankcase oil to help clean oil passages and lifters? How well did it work? What ones do you recommend?