What type of detergent should I use in this washer?

You must use only High Efficiency (HE) liquid detergent, as indicated by 'HE' or 'High Efficiency' on the package. Using regular non-HE detergent will cause excessive sudsing, longer cycle times, reduced rinsing performance, and may result in component failures and mold or mildew. HE detergents are formulated to produce the correct amount of suds for optimal performance.