Yes its a bit of a myth that skinny pigs have dry skin and need oiling, some may do but in this case you would want to see a vet first to rule out mites and fungal infections first as you would with any skin complaint in any guinea pig. I have never once needed to bath or oil Tallulah, she has beautiful chocolate skin that needs no grooming or care at all!
But she does need about 50% more food and does about 50% extra bonus poops, also she gets bored wasily and is hyperactive, and the main issue is keeping her warm enough in winter (and cool enough in summer, she seems to heat up fast as well as get cold easily, on hot days she chooses to sit closest to the fan).
Do you have a good vet nearby
@Oliver_chance ?