Can motor oil be reused after being charcoal filtered or something similar?
Not if the oil has experienced thermal and/or oxidative breakdown. This produces harmful, non lubricating substances and also depletes the additive package in the oil. Synthetic oils on the other hand, with proper filtration can last much longer, but eventually will need to be changed. I am an Amsoil synthetic lubricants and filters dealer. The premise is that these synthetic oils, made from poly-alpha-olefins (group IV basestocks), are much more resistant to thermal and oxidative breakdown. (beware the latest pseudo-synthetics, group III hydrocraked petroleum) The standard drain interval with Amsoil synthetic motor oils and filters is 1 year or 25,000 miles, whichever comes first. With an Amsoil Bypass Oil Filter and spectrographic oil analysis added to the equation there are people running the same oil for years! The bypass filter has a filtering efficiency of 98.7% at 2 microns. At yearly intervals, an oil sample is drawn and sent to a lab which sends a complete analysis to you of y
