Yeh, about 50 years ago this was the case with wax/paraphin/sludge build up, but times have changed. Hate to burst your bubble but penzoil platinum to considered one of the better synthetics on the market.
My go to oils are penzoil platinum in the wife’s enclave. Merc synth. DFI in the opti, merc syn for the kicker,, merc syn hp for Lower unit in both the kicker and main, motor craft 5w-20 semi synth in the old V10 workhorse, sleds get Cat 50:1 in the two older ones and Cat APV in the three newer ones, golf cart, atv’s, gravely mower, tillers, weed eaters, push mower, generator, and other small engines are all on various types of Amsoil, tractor is on a diet of rotella. F250 got amsoil in the front and rear diffs and trans when I switched gears and had the trans freshened. For me, it depends what it’s going in, but almost always lean towards synthetic if available except in the case of the old tractor. Everything gets 91 octane. Since a few of my engines require it, the tank at the house is filled with it, no ethanol and no keeping track of which one needs the good stuff!