I'm going to have to chime in here. WD-40 and other related petroleum based solvents like LPS,PB Blaster will pit and oxidize the paint surface over time.I have seen many postwar Lionel and AF trains ruined over the 40+ years in the hobby because while it looks good at first, WD40 attacks the plastic and the paint pigments.The surface becomes chalky,waxy and pitted.It's like a slow acting dull cote. To shine in polish tinplate and plastic trains,Armor-All is an excellent choice.It's a plastic protectant. I have used it for nearly 40 years on prewar,postwar and modern trains. I am extremely picky/fussy about the condition and appearance of my trains.Armor All works great and is safe.
As far a 3 in 1 oil is concerned.Its OK for prewar and postwar metal to metal areas requiring oil.I prefer Labelle lubricants and lithium based greases for modern era trains with lots of engineering plastics. Labelle has plastic compatible oils.
Vaseline is a no no for trains,it has a high moisture content and will actually rust metal over time.It's original use is a hair dressing-really.
Ricky
