Out of hundreds of shipments to Canada only a few have asked about the oil treatment, as long as the mat and then ensolite were done first, rubbed down well I would imagine no issues but I have never tested it nor had any feedback of a problem so I cannot say for sure either way.
If you live in an area with salted roads then the oil treatment, what they call here is undercoat, might not be the same thing, is generally not needed with modern vehicles due to much better factory anti rust methods. Improperly applied treatments as in the undercoating used here has shown to cause rust if there are unsealed pockets that can trap moisture, and the salt in it, etc..If however you live in an area with major rust issues even on newer cars then by all means get it done.
The majority of deadening of the doors comes from sealing them up per the How To Guide on the site which would not be an issue with the oil treatment.
The outer door skin is primarily for the audio, if one just did a bit behind the speakers on a very well cleaned off air previously oiled, not all the way to the bottom of the door, or did it first then oil treatment, likely just fine as well.
Per the guide, it is not just how much you use of the mat product, it is where you place it as many areas simply do not need it and others very much so.
The foam product goes everywhere possible.
These cars are quite loud in the rear and do not have great access to the cabin vent located under the outer ends of the rear bumper so it is best to seal up all the holes in the area except one or more further from the vent to allow enough flow then treat the trim panels near it to reduce the noise as much as possible.
Once I buy another house, looking for one with a good size shop or big garage I can add on to I will be finishing up the deadening and do the tutorial on the car, it has been a busy year and a half since I bought it, tons of mods, travel, moving, other car and truck projects, trailers, etc....seems I am busier since I retired than when I was running the business!
I think I covered it all, if not let me know so I can get you taken care of
I am on a road trip right now so only online a bit each day.
Sincerely
Rick