Oil on top of childs urine

[Picklepie0]

I have noticed a oily film that's layered on top of my childs urine. He's 5 if that's makes any difference. Any ideas what it could be?
Not sure if it really needs seeing to or if it's normal.

Have you treated him for worms lately? we had an orangey oil as a by-product ...

Well yes but that was over a month ago now, so I can't imagine it will still be in the system.

I saw somewhere on the internet; it's due to your toilet. Get your Kid to go Urine on a Potty and see if that happens again. For my kid, he's 9, I checked in a potty, it's perfectly fine, no oily layer. when he goes on toilet, few seconds after, oily layer forms. Looks its normal as the toilet causes this and Urine Tests are looked fine, nothing serious. If you found already cause for this oily layer on kids' urine, please keep me posted here. Thanks