I’ll put this up again now the shouting has stopped.
I’ve run a pressure jet burner for the last three years on wmo. It needs 100 micron filtered oil so to start I just tipped the wmo through a 100mic filter sock, drained any water, and fed it to the burner. All worked well but the firebox needed the ash removing every three weeks.
Now I’m very curious about things so, after a few months, I drained the wmo fuel tank, fitted a 50-micron filter and off it went again. Ash content was reduced.
I then tested a 20-micron filter and again had a reduction of ash in the firebox.
The burner I use heats the wmo to an adjustable temperature so it will ignite with spark ignition. If I use oil from the top of a settled oil tank it needs a lower ignition temperature than that drawn from the bottom. I believe this is because the non-oil particles settle out and the oil ignites easier if it’s cleaner.
What I learned from this is that the ash is a result of the non-oil contamination. I’m not sure what percentage, it could well be that the additives create some ash, I don’t know.
The wmo I use on my 8/1 is half micron filtered. I’ve had no problem, other than poor starting at minus 6c, but I don’t have enough hours on the engine to give any meaningful results.
I notice Mr Rbodell uses 2 micron and I find his results both positive and encouraging.
I did try ‘1 micron filtered’ oil on an IDI Isuzu engine but it suffered injector coking and unfortunately my experiment was flawed, I used a second hand filter sock from an unknown manufacturer so my 1 micron could have 7! However, it is my belief that the coking was due to non-oil contamination and not burnt additives.
It’s worth noting here that filter efficiency varies. I can’t remember the percentages now but a cartridge filter generally gives better performance than a sock filter. It depends on the manufacturer and filters are made to varying specifications. Some 1-micron sock filters of Chinese origin have been found to only give 12-micron efficiency. As I remember, an ‘absolute’ cartridge filter should be 98% efficient.
Clearly any filtration result comparisons would need to be from the same grade filters.
Any type of fuel that is not completely combusted will leave a residue, so it stands to reason that an engine that has several start-ups, or is running too cool, will produce more carbon or ash than one that runs for long periods at full operating temperature.
Similarly, an engine with worn parts and/or incorrect timing will not combust fuel as efficiently as a new or reconditioned engine.
