It's fine, you can introduce "seafoam", water (yeah, I said water), B-12, or any other kind of varnish remover through a vaccum hose using the sip method. All this is doing is breaking down varnish and any carbon build up in the intake, valve train, and cylinders, or fuel system if you put it in your gas. (Don't put water in your gas...)
I've done it on my exporer several times, the water is a "steam" clean, it worked but not quite as well as a varnish remover.
I'd say doign this as a regular part of your oil change routine is preventitive maint for potential build up down the road. I'm not a mechanic by trade but I know my way around most aspects of a car or truck.
My .02