Dear 56;
The orginal GM 'by-pass' filters should be removed & discarded as they only filter 1/6th of the oil. These are more of a fire hazard than an aid to engine life.
Single grade oil is best too, in this usage.
Multi grades are used/needed in systems with 'full flow' oiling under severe conditions.
The color of the oil (dark) will tell you when changing is needed.
Good luck, John M.....
