|Hi Sue -
The oozing from the rash is not uruhiol oil but is just leakage from blood vessels in the skin (that's the ewwwwww factor). The poison ivy plant itself is not the issue so much as a secondary chemical contained in the plant called urushiol oil. This oil penetrates the skin to bond with lower layers. This bonded entity is detected as a foreign substance and the immune system goes on the warpath. The blisters are the result of your immune system attacking the site which came in contact with urushiol oil. If you have properly cared for the site, then there is not any urushiol oil left to "spread".
Anyway, with all that said back to your questions. That oozing substance is just leakage from your body and no it does not cause the rash to spread.