Stick polythene type damp proof membrane to it or coat it with a decent garage floor paint, that should stop the oil getting to the wood. Rather than making a T would it be better to make two separate trays to make it easier to move/store/clean?
For years I used the side panel of an old washing machine to catch drips from a vintage mini.
Cost me nothing - any white goods should do the job. Topped it up with sawdust to absorb the liquids.
David