As to the OE, what do you think they would say to the HPL EC product? I can tell you - "not recommended". It would impact your warranty as such. Anything beyond regular as-approved/spec'd motor oil is not kosher by any manufacturer I've ever heard of including additives, flushes, off-spec oil (including viscosity) etc....they will all be treated exactly the same if you blow up your engine and show them that detailed receipt when they ask. Of course the HPL product is just an oil so a bit different than the solvent flush products but in the end, call Subaru and ask them how they feel about running a straight 30W oil in your engine...I think you came in late, even with the 4-page buffer
I thin O/K and I are roughly on the same page- flushes may or may not work without harming the engine; all are certainly NOT created equal. If you want to use a flush, go right aheadā¦ weāre just not going to recommend doing something to your engine that the manufacturer clearly says to avoid and has voided warranties for using.
Now that weāve got HPL available, thereās really zero need to ever use a flush. Fill your sump with HPL and put a 99%@20u filter on it, and you will definitely end up with a cleaner engine without any additional risks. But, if you like living dangerouslyā¦ experiment away.
Personally I come here for the explosions & horror stories, just like nobody watches NASCAR for the actual racing. They watch for the potential carnage!
What I'm doing is hardly experimenting anymore than the folks touting the HPL EC here. Where is the hard evidence/scientific testing that many on BITOG demand about anything like this? It's not here. It's really just the same feel-good product that folks want to work so badly as many other products discussed ad-nauseum on the BITOG that in the end, are all based on a "hope" that they work and do what they are sold as doing with all sorts of "testing" etc. here trying to "prove" that they are working better than some other stuff.
Now back to using my HPL EC, HPL oil, LM Engine Flush, MoS2, Ceratec, and anything else I can experiment with!