I bought a bottle of Ultra Pure today with the intent to change my horn(s) over to synthetic oil. I also bought the same brand slide grease. My question is... can I adequately clean the old petroleum-based oil off myself with warm water and detergent, or should I have the horns chemically cleaned before using synthetic oil? Is there a problem if the two oil types mix? One horn is a 6 year old Strad that has had Al Cass in it since day 1. The other is a '59 Connstellation that I have on loan and considering buying (will only change the oil if I actually buy it).