yes cats do help burn oil but with that much oil being lost you would DEFINITELY see blue smoke out the exhaust because oil is not as combustible as fuel which is what the cats are meant for. and oil burning in the cats would also burn white

 

also bad cats would cause an engine to burn oil.. my father had a 90 ford he bought new... year later started using oil profusely...they put a new engine in it under warrenty..3000 miles later...another new engine...2000 miles later he brought it in to have it checked out.. and it was like 3 quarts low... and they were getting ready to pull the engine again and a rep. from ford called and said to take the cats completly off.. ... and that fixed it... back then they didnt even install a new cat...they just cut if off and added pipe