If you dont know of such service doesnt mean it doesnt exist - it used to be called "tappit setting" in Pakistan. Its mandatory to be done otherwise you will burn the valves. (pricey business) btw - for your iridum plugs not lasting 150K kms you have to make sure they are have a solid platinum disc fused to the negative part of the plug too, There are many versions of similar spark plugs - some have precious metal on positive side only (low mile life plug) while plugs with precious metal on both sides have very long life. - e.g. denso IK series have plug life as long as copper plug only while SK series plugs (4 times more expensive) have life 5 times longer, both are called iridium plugs.
btw - the fuel in USA is mixed with ethanol - the same stuff that was introduced in Pakistan and mechanics were calling it "kemikal hai - pitrol nahi" - if you recall history.
Im talking about global service manual (its written by Toyota Japan)
btw - Your "feel" is invalid as you also claim to do 200 kph on a Pakistan motorway in a corolla. - I will believe the actual manufacturer and also lube blender and plain physics - heavier fluids have more friction (its called viscosity) and if I want a "Pakistani POV" like yours - I have hundreds of clients reporting the same which is that mpg takes a solid hit when they use a heavy lube oil.
typical answer of green passport holder to deviate - you yourself claimed that "why touch an engine if it starts and runs" - aka "chalti ka naam gaadi"
by that rationale ustaadified, direct fan, tap water as coolant, mota haail, tire sourced engine mounts, dragging brakes and cheap taping on wiring along with a long laundry list of classic desi repair cars - also "run" but will be considered "running scrap" - but hey "chalti to hai naa"
I got them for free (liquid molvi injector cleaner) - tried on an actually blocked cat converter on a chevrolet silverado pickup, didnt do anything at all. waste of money - welded new converter to get truck working and pass onboard readiness monitors.
this was sold back in the mid 2000s too, I used it in Pakistan on a jdm shahkaar accord (cf3) - didnt do anything to unclog a blocked cat, had to replace it - car was owned by "sunglasses welded on face used car salesman" aka "showroom wala"
btw - cat blockage is checked by measuring pressure differential across the converter - not the transmission shifting or feeling the pickup.