Greetings John. I just looked at your Crown briefly but, I think you have all the good equipment on your bus. If my memory serves me, you have a late model Crown powered by a Detroit Diesel engine and an Allison auto trans.
You need to change the coolant filter at least once a year. The filter number should be on the filter. The coolant should also be checked for ph with some coolant test strips available at most car parts stores. If ya must add water use the distilled water sold at the food market for steam irons. The ratio between coolant, the green type and water should be 40%coolant and 60% water. The coolant should be tested for cold weather too. Check the trans fluid too.
Ya got a great bus, so go for a ride. And get that paint job finished. Ya got a good bus, use it. Frank