If the Oak has been stained, the filled holes can be made invisible. If it is unstained, they can be almost invisible unless someone gets right up on it and looks for the spots. I wouldn't use plastic wood though.

Before you do that though....are you sure you can't find pulls the same size? I'm sure you've tried Home Depot or Lowes. Have you also tried specialty kitchen stores or local hardware stores?

If they did indeed use furniture pulls, why not try to get replacement furniture pulls? They'd at least have something close to what you want to replace with. How about a decorative back plate that goes behind the pull? That would cover the existing holes......I'm just trying to save you the effort of filling the holes since there's probably a lot of them.

The cabinets are stained and you're right there are alot of holes to fill.

I've looked for furniture pulls that might work but have not had any luck finding something that works with the style. I have thought of the decorative back but it would make the pulls stand out too much. Even the bin pulls are too heavy.

So they can be invisible! What product do I use?

The bin/cup pull is too heavy looking but it would cover the 2 holes in the cabinet from the previous hardware.

I think I just want to fill the holes and use something I like instead of trying to find something that will cover the holes.

That's my concern. What product would do this?

Go to a good paint store and buy the colored putty used to fill holes in hardwood floors.
If it is not a good enough match you can mix multiple shades to get one that matches better.
Another method would be shellac sticks frm Mohawk finishing supply, but they need practice to melt and work.

Have you considered using a back-plate behind whatever pulls you like? Here I'm thinking of 1/4" or so thick wood that is glued over the holes and serves as a "mounting/back-stop" to the new pulls. This new wood can be cut to whatever shape looks good and stained or painted to "taste".

I too wonder about the 2 1/2 holes, inches I assume. Or are they two holes 2 1/2" appart?

Oh sorry, I wasn't very clear. Yes the holes are 2 1/2" apart.

Ok, now it is easier to work the question. I assume the holes are less than 1/4" in diameter, say a Number 10, bolt. I don't know what the normal/current spacing is, I assume it is different than 2.5", or is the problem you want to mount single hole pulls? That's what is on my kitchen cabinets, knobs with only one hole in the center left/right and maybe a bit above center top/bottom, going from recall. If this is your case, the wood filler seems the most productive possibility. I am not confident about being able to make the holes disappear unless you are painting. Careful filing and sanding to a plane, and paint will make the holes invisible.

If you can utilize at least one of the existing holes for new hardware, the second hole will be visually masked by the replacement handle.

That being said, an approach I've used with success is to cut wood doweling a hair longer than the door/drawer thickness. Usually 1/8" dowel will fit in the old screw hole, but if not, you can run a 1/8" drill bit through the hole. Then apply a little wood glue to the dowel and tap it in gently from the front until it's flush with the door's face. Wipe the exposed dowel end with a damp cloth to remove any glue that might have squeezed out. If you think it's necessary in order to get a perfectly smooth surface, apply a little wood filler with your fingertip. Then, when dry, sand very lightly with 220 sandpaper and stain the dowel end to match the cabinets. (Since this is end grain, you might want to experiment on scraps of doweling and lighten the stain until it matches the cabinets.) Apply a little polyurethane with an artist's brush to seal the fill.