What type of detergent must I use with the WFW9200SQ?

You must use only High Efficiency (HE) detergent, which will be marked 'HE' or 'High Efficiency' on the package. Using regular non-HE detergent will create too much sudsing, likely resulting in washer errors, longer cycle times, reduced rinsing performance, and may even cause component failures or noticeable mold or mildew. Follow the detergent manufacturer's instructions to determine the correct amount to use. (Page 11)