Oiling plastic does not soften it. Plastic gloves are not necessarily cheaper, especially if you have to buy a new one next season. But with gloves and friends alike, the effort and time will be well rewarded. Most gloves are designed with built-in hinges which allow the glove to be opened and closed easily. The glove should close just like your hand at rest with the fingers folding at their hinge where they join to the palm.
Some players prefer to break a glove so that the little finger and thumb tips come together.
There are a few glove models designed to accomodate this break. These gloves usually have a series of vertical laces securing the heel pad. These laces allow the glove to fold across the heel. It is possible to break down the thick heel pad on the former glove type, but it is preferrable to buy a glove designed to break to your specs than to try to modify the break angle. I always clamp my jaw and shudder when a player tells me of the best way to break-in a glove.