LC20 mainly deals with oxidation. I don't think it claims anywhere to condition seals, and I wouldnt expect it to.
Seals can last indefinitely if treated well and kept clean. My 28y.o. MB diesels are a testament to this, even after 240k miles. LC will keep things clean and decrease some of the issues that dirt and grime can play on seals, IMO.
He doesn't say "Softening up seals" on his new site but he does use the words restore and recondition seals and makes them more pliable. This to me would suggest softening but I think it's creative wording.
Is there any kind of cleaning action to LC20? I'm thinking of using it in my gf's explorer to see if it cleans things up any. I'm mainly just trying to use up the gallon jug I have. I used to use it in my old pickup, but I bought my jeep new, and I figured it really didnt' need it. Her explorer on the other hand has 95,000miles on it. I just figured I'd give this a try and use it up before trying some AutoRx in it.
I don't know if it cleans as I have not obserrved any cleaning, the engines have always been clean. =\
With the ongoing avancement and improvement oils I will not use it again. I just don't see how it is helping anymore. I am about finished with my last gallon.
LC20 can and should be run the entire OCI and add an ounce every 1000 miles. It is not specifically a cleaner like ARX although it is supposed to do some cleaning. it is ongoing maintenance, not a binge/purge cycle.