I don't see the point in putting an oil over a dried top coat, unless it is just a carrier for the wax. Wax starts off as a solid and is usually mixed with oil and or mineral spirts to make a paste or liquid. If you are starting with solid wax then I think any oil will do. If you are starting with paste wax then I don't think you need to add any more oil.
Honestly I did not mean to offend at all and I am happy you are getting some shop space with enough electricity to run your machines. I went two years with a garage shop that only had two 15 amp duplex outlets, upgrading the service was the one of the happiest days of my life. Normally I don't play safety police or code enforcer because the world does not need more fun police. In this case it is warranted because you said your friend is an engineer, he does tons of this stuff in his spare time and used to do it for a living. So other people reading this thread might assume it was done correctly. Now I don't think people should get advice on the internet but that is the world we live in. If you are happy with it, I guess that it is good enough. But also keep in mind one day someone else will own your house and maybe assume that white wire is a nuetral and not a hot. A house I owned was wired by the prior owner, also an engineer. He had one of the duplex outlets wired to two different breakers. I have no idea why, but each side of the duplex was on a different breaker. Well I had assumed I turned power off to the outlet when working on it and got a nice little 110 shock when I touched the other side. I don't know if that is code or not (I assume not), and it is my fault for not checking both sides with one of those little voltage detectors. But it is certainly not normal.