Our allergist also told us to use Aquaphor or petroleum jelly on my DS' eczmea. The idea is to seal in the moisture that's already there so the skin doesn't get dried out. He recomended using it after a 15 min. soak in the tub. He also prescribed a steroid cream, but steriods have a way of thinning the skin over time and thin skin on the knees and elbows is not good for a little boy!
So, of course there was no way I was going to put that stuff on his skin so I use a cream called Lantiseptic. It's lanolin in a beeswax base and it is like a miracle for his skin. Lanolin as many of you know, is the closest substance to your body's natural oil and the beeswax helps seal the moisture in. It's a bit sticky, but I find that helps keep his hands away to prevent scratching it. We put it on at night and put him in footie pajamas so he can't get to his legs or back, where he scratches most often. When we first began using this stuff I took his pj's off the third morning and cried because his skin looked so beautiful. We've been battling it for a year and I was starting to think he'd never have normal skin again. I highly recomend it.
ETA: Latiseptic does have petrolatum and mineral oil in it, but it's 50% lanolin, then from most to least are beeswax, fragrands HEEDTA, lanolin alcohol, mineral oil, oxyquinoline, petrolatum. Then just the misc. like purified water, sodium borate, and sorbitan swsquioleate.
So, if you're looking to avoid them entirely this is not the cream for you, but they are in such small amounts here as opposed to pure petroleum jelly or Aquaphor which is a petroleum jelly base, that I am comfortable using them.