Direct injection diesels can stand some ether to aid in cold starting, mostly if they were not designed with an alternative starting aid. But never use ether on an engine with pre-combustion chambers, which most of your compact diesels are running nowadays. The JD salesmen mentioned earlier says JD is direct injected? Hmmm, OK, maybe I've been away from the Yanmars too long, but many were definitely pre-combustion as I remember them. All the Kubotas that have been produced in say the last ten years plus are also pre-combustion (TVCC, three vortex combustion chamber). Basically combustion of the "pre-charge" happens in a very small area prior to "propogating" to the cylinder. This is the main danger of using ether in these engines. The cylinder head and pre-combustion chamber are not designed for this type of rapid expansion and can cause some major damage. Using WD-40 instead of bleeding properly is a pretty /w3tcompact/icons/cool.gif little trick, but I'd prefer to bleed the system properly. Many, maybe even all the engines I have rebuilt, do to cracked/broken rings and ringlands, cracked cyl. heads, blown out pre-combustion chamber caps, had a very distinct odor of ether in the air cleaner area, for what it's worth.