Translation:He was washing the sink and the kitchen stove.
In English "He used to wash" and "He was washing" have two distinct meanings. He used to wash implies something he doesn't do any more, he was washing would precede a statement about eg. what happened while he was washing .... Can anyone advise on the difference in Romanian?
El spăla can mean either "he used to wash" or "he was washing".
You can say El obişnuia să spele to make it clear that you mean "he used to wash".
I don't totally agree with your explanations of the two forms. "used to wash" means washed habitually (in the past), it isn't necessary that the washing has stopped in the present but very often will imply that. "was washing" means that at that moment in the past he was in the process of washing - that the washing was in progress.