Can I use regular detergent in this washer, or do I need a special type?

You must use only High Efficiency (HE) detergents marked with 'HE' or 'High Efficiency' on the package. Regular non-HE detergent will create too much sudsing with this wash system and may result in washer errors, longer cycle times, reduced rinsing performance, component failures, and mold or mildew. HE detergents are designed to produce the right amount of suds for optimal performance. (Page 11)