spilled oil over my keyboard

As far as I'm aware all 15" unibody use identical keyboards (same model number of computer since 2008). Maybe 2012 model different. That said I was able to remove milk from 20-25 keys using an x-acto knife a very pointy tweezers and "canned air".

The problem with these keyboard and impossible to repair is that the three layers of plastic are glued together! In the old days you could peel apart the layers and clean with dish soap and re assemble.

If you have fewer than 10 affected keys it would be worth the effort of a top-side fix as long as you realize the risk of needing to use an external USB keyboard while the replacement comes should you break it.

If you look at any single key contact you can see the two layers with the crossing traces going to the center. The process to clean out the milk etc. is this:

On the TOP LAYER, determine the direction of the trace, example horizontal. Now make two in incisions on either side of the center cutting in that same direction on either side of that trace. Cut through top layer only and INSIDE the AIR BUBBLE surrounding the center. Now use the likes of a SEWING NEEDLE to lift up the top layer between the slits. Next use canned air to vamoose the contents in the air pocket mucking things up. In my case it was milk. If its thicker like oil you may likely need to use a solvent to flush it out.

The reason your repair is temporary is that there is a little capillary tube that draws liquid back into the contact bubble. If you get even temporary relief from alcohol cleaning you are a good candidate for topside fix.

I had 100% success with the 20+ affected keys. Took a couple hours. Sadly a cat knocked a whole glass of water on same fixed keyboard 6 months later and killed it.

If you manage to kill your power switch I have a "jump start" process. I have a YouTube video showing how.