Can I use human shampoo on guinea pig bum?

[machuandpicchumummy]

Cleaned my long skirted boar's grease gland at the weekend with coconut oil and plain water which got the matted bits of grease around the gland off but has left his lovely long skirt a bit oily. Could I use a tiny bit of human shampoo to get this off or is it best to use a guinea pig specific one? Would only be on his long skirt so not near eyes or ears etc

 

[Piggies&buns]

You could use a very small amount of baby shampoo (due to it being mild) but ideally a guinea pig should shampoo would be best