What type of detergent must I use in the WFW86HEBC1 washing machine?

You must use only High Efficiency (HE) detergents, which will be marked 'HE' or 'High Efficiency' on the package. Using non-HE detergent creates excessive sudsing due to low-water washing, which can result in longer cycle times, reduced rinsing performance, component failure, and buildup of mold or mildew over time. Always follow the manufacturer's instructions to determine the correct amount of detergent to use. (Page 6)