I'm wondering if you can chime in and help me over-think this. Why? Because that is what we do here on BITOG, right? My daughter's 2013 Corolla has about 196k miles on it. She bought it from a friend of mine who is a regional sales guy. He states that he always had the oil changed by a guy he knows at a Valvoline Quick Lube place and used full syn oil on 6k OCI. I changed oil on it and put in Valvoline FS HM. That was about 6k miles ago and it has burned about 2.5 quarts in that time. I changed out the original spark plugs, they actually looked pretty good given the miles on them; not oily. I changed the PCV valve (original wasn't bad either). I've done a little research and it seems there is a known issue. The pistons have four holes drilled in the oil ring groove. Those holes get clogged up with gook, so the oil can't drain back down into the crankcase, so it is forced up past the compression rings with nowhere else to go. The fix is to remove the pistons, clean out the grooves and holes, drill two additional holes and put new rings on. I am NOT going to do that. I was thinking of switching it to Castrol GTX Ultraclean 5W30 and adding a 1/2 quart of MMO. Then about a week ago I was reading the thread here "M1 vs PUP observations". Excellent thread BTW. That got me (over)thinking, maybe I should run PUP with their piston cleaning claims. But, PUP would be about $8 more a jug vs. the GTX. I'd love to hear everyone's thoughts as they over-think this with me.