honestly man i’ve used regular refined castor oil from the health shop before and it was totally fine - just a bit thicker than the pharma grade stuff. as long as you're running it through a .22 filter it’s going to catch any of the nasty stuff anyway. just be prepared for a slow as hell filtration because castor is like maple syrup lol. definitely wouldn't call it dangerous if it's clean and filtered properly.

the main difference with the super refined stuff is just the clarity and how much it pisses off your immune system. regular refined might give you a tiny bit more pip or redness but if you aren't sensitive it's usually not a big deal. i’ve pinned worse lol! just make sure the gso and eo are mixed well so it's not too thick to actually get through the needle.

i’m in the uk too and i know exactly which oils you're talking about - they're fine for home use. the pharma companies just charge a premium for "super refined" because they have to meet insane standards for hospitals. for a home brew the .22 pvdf filter is the real hero here. just take your time and don't try to force it too fast or you might pop the filter housing.

castor oil is a beast to work with because it’s so dense but it’s awesome for long esters like deca or test u. i wouldnt stress too much about it being "dangerous" - as long as its refined and not some cold pressed stuff with bits of bean still in it you're golden. the eo you're adding will help thin it out a lot too which is good because pure castor is like trying to push glue through a pin lol.

man i’d say go for it. i’ve been brewing my own for years and used all kinds of refined oils when i couldnt get the fancy stuff. the pvdf filter is legit so it'll do the heavy lifting for ya. just keep an eye on the site for the first few shots to make sure you dont have an allergy to that specific brand. usually its totally fine though! good luck with the brew.