[quote=SaraRPs]
You said that his weakness included extremely cold environment and her ice can get VERY cold.
[/quote]

his weakness is cold environments so unless your character can make an entire area cold enough to cool liquid that is hot enough to melt metal then her ice powers will not be as effective Against the oil. Also if he gets angry enough he could make his oil much more hot than normal so if he gets super angry then his oil heats up to even more extreme levels.