DI engine with high miles isn’t worth analyzing because it “has had an easy life”. DI engine with low miles “hasn’t been driven enough to see the damage”
These guys are sure though, that DI engines and dillution ARE a problem, even though there’s zero evidence. Apparently it takes 200k miles of driving 5k miles a year for dilution to take its toll, for everyone planning to keep their cars for the next 4 decades
That is because you took all the nuance out of everyone's equations and simplified it into something that is unintelligible.
Fuel dilution will cause damage if the oil isn't changed regularly, or if it is changed at long intervals where fuel starts to exceed critical levels. The reason fuel dilution happens is due to fuel being injected at high pressures directly at cylinder walls of small turbo motors that run rich to maintain lower cylinder temperatures, thus not burning all said fuel, which gets scraped its way into the oil by the piston and/or gets pushed through as a result of blow by because of high cylinder pressure of TGDI engines.
The reason 100% highway mile TGDI engines aren't impressive, is that they are effectively, running on vacuum, with much lower cylinder pressure and running with as little fuel as possible, so if there was fuel dilution, it was probably a smaller amount, and this is aided by long highway trips where the engine oil reaches the 60C temperature it needs to separate the fuel and evaporate it back through the PCV system. This is why TGDI engines are not recomended for lots of short trips and cold weather, that the oil doesn't reach high enough temperatures to allow for the fuel to separate and evaporate. Also most people end up lugging the engine more in stop/go traffic in cities, increasing cylinder pressures over and over for no reason.
In the city, where you drive very short distances, over short periods of time, or sit in traffic idling at very low RPM, your engine oil simply doesn't warm up as fast. 30 minutes or more are required. See this video for actual testing and data: