Is 'Bahasa Gaul' hindering my ability to pass formal proficiency exams?

I’m preparing for an Indonesian proficiency exam, and I keep catching myself sprinkling in slang because it’s how my friends in Bandung speak. I’m worried I’m going to accidentally use a 'gaul' term in my writing section and lose points. Does anyone have a strategy for compartmentalizing these two registers—formal and slang—so I don't mix them up during the test?