I don't know what oil costs, but where I bowl league, they oil fresh for us, but don't touch it again until Saturday. Then maybe a few other times during the week. The owner back in the 80's used mineral oil instead of whatever was normal, and for two reasons: mineral oil won't catch fire like lane oil, and kids could get the oil in their mouths and not get sick.
Don't know how mineral oil would hold up on today's balls.