Gas oven goes out while in use

Hmmmmmm? Oil in the propane lines is never a really good thing. That being said, I would proceed with some of the earlier suggestions with regard to cleaning the thermocouple and making sure that the pilot gas tube is free of debris. Can you get us a picture of the pilot light when lit - I'd like to see it's color and flame profile. Butane and some lower grades of propane have been known to contain small quantities of impurities or even "sludge". It would be wise to empty the bottles fairly often to keep stuff moving along in the lines. Empty one (A), change over to the other bottle (B), fill the empty one (A), empty the current one (B), change over to (A) and so on.

Cleaning the propane lines can be tricky, dangerous and not for the feint of heart or inexperienced. Keep us posted and good luck!

Cheers!

Mike