It’s like, okay but not ideal since ketoers are encouraged also try to avoid processed foods which while may not kick you out of ketosis are just not…good for you on an overall level.

If cold pressed then yes. Avoid all hydrogenated oil.

You can. It has no carbs. It’s all fat. So why not.

I eat it all the time; have been keto for 4 years now.

So I read some more about this. If its cold pressed oil, and not processed, then mustard may be okay. But largely, processed poly unsaturated fats are not okay since they are processed.