I believe my mother used to use Oil of Eucalyptus (available from chemists) to removed bicycle chain oil from our socks when we were young ......... if it is still available it may be worth a try - just dab it over the area to be treated, leave for 10 mins or so then wash the clothing in the washing machine as normal.
The best way I've found to get rid of oil or grease stains is to rub some fairy or washing up liquid into the stain (neat) and leave it for a day before washing it in the normal way