Hi, i've been an oil /oftec engineer for too many years to mention, and have dealt with hundreds of oil run outs.
if youve found 'muddy water' in the burner pressure guage takeoff point, then you will have problems again.
soon!
there is water in your tank, and it needs removing.
oil floats on water, so you will find there is a layer of water in the very bottom of your tank, near the bottom of the oil valve.
it will get through in drips and drabs, some particles so small you wont notice, or just an occasional 'lock out', but that water is rusting up your oil pump.
it should be dealt with by professionals, 600A qualified, but basically can be syphoned out of tank by placing a copper tube right to the very lowest point of the oil tank, connecting a hose to the tube, and sucking!
WITHOUT ANY SPILLAGE, the draining fluid should be directed into containers, and 'muddy water' will be apparrent in the bottom of container. when clean yellow kero runs through, stop,and dispose of contaminated oil/water at local facilities, not down the drain!