yes you can, but it is best to fill the filter at least half way and spinning the engine over on the starter motor with the central dizzy cap (petrol?)lead removed to prevent the engine running dry whilst the filter gets filled, so you'd be back to square one. do a full oil change you then know its got the right amount of oil in there and its fresh stuff, draining the oil is just a 13mm sump nut to undo.
https://club8090.co.uk/wiki/Pe ... oil_change" onclick="window.open(this.href);return false;
Whack a new air filter in there whilst your at it, that would probably help more than the oil change with your HC's