On Thu, 9 Apr 2009 02:50:05 -0700 (PDT), Frank Thompson
wrote:

Do any pressure washers have anything other than just one rate of
dilution (i.e. rates different from standard rate for cleaning
liquid)? If so, what brands?

I believe some models are adjustable but a common fixed ratio is 7:1

Use this calculator for higher ratios.
http://jansson.us/mixingratio-concentration.html