When I served in the USAF as a body/general purpose vehicle mechanic I was assigned to Eielson AFB. that's in ALASKA near Fairbanks. Let me say that environment is pretty tough on vehicles! Tires can break at 70 below zero (f). I have maintenance stories that would curl the paint right off your truck!
The base was heated via a steam plant that was plumbed to every building on base; so we had PLENTY of distilled water for the radiators, the UN-treated water in AK. leaves much to be desired. It's FULL of minerals, it could probably float a horse shoe. So we didn't have the issues with that at all.
We put Marvel Mystery Oil (MMO) in power steering pumps, in the hydralic systems of the heavy vehicles, plows, Osh Kosh trucks, truck mounted ribband blowers, buses, trucks, cars, everything. I know it went in to the hyd. oil but I'm sure it did not go into the gas unless WE put it there for a specific purpose.
Berrymans' can dissolve plastic carb floats (in motorcycles) so I like Sea Foam, it's gentle and when used regularly keeps the fuel system in tip top shape. The label describes it's use in oil.