I purchased Armstrong self-stick vinyl tiles to install on a portion of the floor in my kitchen. Right now, the subfloor is OSB, and I'm not sure if I can install directly over that? I would prefer to, as I didn't plan on removing the dishwasher to tile underneath it- and if I need to lay an additional layer of plywood down, I'd HAVE to pull out the dishwasher so that I don't wedge it in there by adding additional height to the floor.

Basically, the OSB that is down is pretty much level, except for one area which I think I can level out by sanding and possibly using some kind of wood fill... the OSB has been down for at least 25 years or so, I'm assuming- any ideas or suggestions on ways of ensuring that the vinyl self stick tile stays in place w/o any problems without having to install an additional layer of plywood over it?

Thanks!

You do not install vinyl floors over any subfloor, you need a suitable underlayment.

Jaz

Lay down 1/4" cement board. Use thinset under it and screw it down. Unscrew the dishwasher from under the countertop and push it as far in as you can. Lower the front legs on it and prop it up while you put cement board under the first few inches.
That's what I did when I painted my concrete in the kitchen.