1.5 should be fine, as 9A is within the ratings I can find (vary from 10-19A) depending on application, and I very much doubt you'll be making full use of the 9A constantly.

Personally, for something that's flexing a lot, and with the potential to cost money should it fail, I'd spend the extra money and get some ChainFlex cable from Igus - https://www.igus.co.uk/chainflex/motor-cables
Standard ChainFlex CF885 Motor is £4.02/m or £3.27/m if you buy more than 10m, although that has no oil resistance.
If you want Oil Resistance, then look at something like CF30