Replaced the air filter on a '78 318 2bbl recently. A paper filter of the same type as the one replaced. Time between changes about 1 year/5000miles. I put the used filter in a bucket of water with some detergent and let it soak for a while before flushing and drying it. My question is as follows: The old filter now looks clean, but has it somehow "lost its filtering powers" in the abovementioned process? I know K&N make a big deal about their filters being washable, but as far as I can tell, so are the cheap paper ones.