An emulsifier/demulsifier system is selected for use with emulsified oil systems such as metal working lubricants. The emulsifier includes an alkyl substituted succinate such as polyisobutylene succinic anhydride. The demulsifier may include a low hydrophilic lipophilic balance surfactant. Other emulsified oil systems which may benefit from the particular emulsifiers and demulsifiers includes oil field chemicals such as drilling fluids and cementing chemicals, paper chemicals, explosive emulsions, rock drill lubricants, and mining lubricants.
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