A known fix for sticking oil rings in certain engines is to drain half the engine oil, and then replace with kero (=50:50 mix) and then fast idle the engine for 15-20 mins at 1500-2000rpm. No load, mind you. But you need to get the oil throwing around the underside of the pistons, etc.
Then drain and replace filter. Fill with normal oil. Ideally do the next change at half whatever your normal interval is and then revert to 'normal'. I've done this myself on a few engines and had spectacular results (all high-mileage). 8-10 ltrs / 10,000kms oil usage down to under 1 ltr. That sort of result. Can recover an oil-burner if it's the rings sticking. Won't help one where the rings are just flogged out though. Sometimes the stuff that comes out of the sump is a bit terrifying. I've been know to refill with a 50:50 mix of cheap oil and kero and have an immediate second go at really bad engines.
For a well maintained engine a flush using 250-500ml of an 'oil thinner' before each change won't hurt, and might help dislodge anything trying to build and help get a more-thorough drain-out. But I'd use regular kero quite honestly. $1.50 a litre is a lot better than $30/250ml and it is essentially very similar (some might say the same).
So not 'snake oil', just 'expensive kero' 
In the old days, you'd use diesel-grade engine oils in carby petrol engines to clean them out. The diesel oils had a higher amount of detergents and dispersants and would really effectively clean out an old engine over time. Usually meant quite a few oil and filter changes that became less often as it it did it's magic. The kero flush gets you 80% there in a single shot, quickly.
DiscoClax
'94 D1 3dr Aegean Blue - 300ci stroker RV8, 4HP24 & Compushift, usual bar-work, various APT gear, 235/85 M/Ts, 3deg arms, Detroit lockers, $$$$, etc.
'08 RRS TDV8 Rimini Red - 285/60R18 Falken AT3Ws, Rock slider-steps, APT full under-protection, Mitch Hitch, Tradesman rack, Traxide DBS, Gap IID
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