An increase in household oil thefts in Buckingham and Bicester has prompted police to issue a warning.
Last month, seven homes in Twyford fell prey to oil thieves during a single night.
Thames Valley Police is urging people to be vigilant especially during oil deliveries and report vehicles and persons that look out of place.
Advice to install a flow alarm and put padlocks on tanks is also in place.
To find out more about oil tank security visit www.stopoiltheft.co.uk