Per the Sea Foam can instructions - adding 1 oz. Sea Foam per quart of oil capacity (i.e. 5 oz. per 5 qrt. oil sump capacity) for up to 300 miles for moderate cleaning of engine internals : *If you follow the instructions by adding Sea Foam to oil right before you plan to do an oil change ( <300 miles) how bad could this really be for your engine ?? I just want to do a little cleaning of oil journals , ring packs , etc. every 3rd oil change that the oil may otherwise miss - your experiences / thoughts ?