What type of detergent must I use in the WFW96HEAU0, and what happens if I use the wrong type?

You must use only High Efficiency (HE) detergents marked 'HE' or 'High Efficiency' on the package. Using non-HE detergent will likely result in longer cycle times, reduced rinsing performance, potential component failure, and over time, buildup of mold or mildew. Low-water washing creates excessive sudsing with a non-HE detergent. (Page 7)