"He washes until he gets tired."
Translation:El spală până când el obosește.
nobody is using this form, unless there are two persons involved, like ”john washes until jim gets tired” (imagine john is washing something while jim is chopping wood, and Maria says, pointing to john ”el spală până când” - moving the finger to point to jim - ”el oboseste”). In all the cases when ”he” is the same person, a Romanian will say ”El spală până (când) obosește” (the most of the time, ”când” is also omitted, but there is no second ”el” there).
Moreover, ”washes” is transitive in Romanian, it needs a beneficiary of the action. If he washes himself, we have to say so. Otherwise, when we say ”El spală”, without adding anything, we invariable understand ”he is doing the laundry” (washing clothes). If he is washing dishes - ”el spală vase(le)”, or washing himself, we have to say so, i.e. to use those reflexive thingies...
Therefore the most suitable translation here is ”El se spală până când oboseste”.