Ron, Filtration does nothing to replenish viscosity improvers and other additives, nor does it prevent the oil from becoming acidic. Tugs and ships have bypass filtration systems and/or centrifuges to clean the oil, and no, they do not stop and change oil at sea. In most cases, there is enough "make-up" oil needed so as to preclude frequent changes. Much of this comes from the cylinder lubricators. You may be sure they do not use paper towels to filter their lubeoil. Regards, John "Seahorse" Reply to: John@Camm.us Ron Rogers writes: Although I imagine that it is wise to exercise the wing engine, wouldn't the use of a Gulf Coast or other oil bypass, "depth" filter preclude the need for stopping the main engine. For arguements sake, do tug boats and similar commercial craft stop their engines to change oil?

Amsoil makes a bypass oil filtration setup: http://www.amsoil.com/StoreFront/bf.aspx Here's a good article from Gulf Coast Filters that deals with extended oil changes: http://www.gulfcoastfilters.com/how_do_i_eliminate_routine_oil_c.htm Keith __ For THIS I bought a computer? ----- Original Message ----- > > Although I imagine that it is wise to exercise the wing engine, wouldn't > the > use of a Gulf Coast or other oil bypass, "depth" filter preclude the need > for stopping the main engine. >