I think the quote from Terry pretty much sums it all up, but I'll add support
I've used, and use, both. I've strayed from LC20 for maint dose to ARX at the moment because:
- my oil doesn't need any help in terms of oxidation according to UOA results
- ARX is more effective for the kind of "help" my vehicle needs
- I found an in-country source for ARX, but LCD products are still stupid-expensive to ship here
IMO, LC and ARX have their own different place. LC is reportedly superior with varnish-type deposits and oxidation issues; ARX with carbon, rings, sludge and seal issues.
My engine "problems" include generally better performance while using ARX (maintaining ring pack cleanliness?) and one minor ticking HLA. LC did nothing for my HLA, although I never tried the "shock dose". ARX clean/rinse improved the HLA but hasn't eliminated it. ARX maint dose has been slowly improving it I think, but it is taking so long it's becoming hard to tell in any definitive way.
I admit that I'm still very slightly concerned about the compatibility of my chosen oil (GC) and ARX based on observations and resulting discussion from
this thread . I don't believe that any harm is being done, but very few REALLY understand how ARX works and there have been a number of references by Frank that ARX will "clean" other esters out of your oil "no problem". He's also said things like "Oh, you didn't mention you were using GC! That has esters in it!" IMO, this kind of action by ARX changes the characteristics of my chosen oil, which I chose for a reason, and I don't like that. Nor do I want my ARX maint dose wasting its time/effort cleaning other esters from the oil. I also hadn't really planned on changing my chosen oil since GC is working so well for me, is easy for me to obtain (compared to the US) and is well priced (at $8/bottle compared to all of the other overpriced oil in Canada).
Conerns aside, I don't want to detract from ARX, I think its a solid product that has proven to have many benefits for many people - including myself.