I use it in a '03 vintage, power dense pushrod v-8 domestic with port injection. Use it in air cooled tractor, pressure washer. Won't put it into a modern Dexos required 5w-30 V-6.
Troubles in the applications I choose? None.
It's a stonkin' hard a**ed oil whatever you put it into that may have had a x-30 app, being it's on the thinner side of a 40 grade. But I won't put it into a sensitive, emissions legal machine unless directly called for.
That pushrod '03? Catalyst deleted and tuned to absolutely ignore post catalyst sensors. Reasonably, perhaps logically; it wouldn't be a worry in any 30 weight application that's not worn so bad that it must outright burn its sump.