Police were called to the M6 northbound on Friday afternoon following a report of suspicious activity around a white Ford transit van.
When officers arrived at Corley services at around 2.30pm two men ran from the scene across fields behind the service area.
One was detained by officers, arrested and taken into custody in Leamington.
Another male is still outstanding.
Police and the Highways Agency closed the M6 in both directions between junctions 2 and 4, as well as other roads including an overbridge.
Traffic was queueing back as far as Rugby.
A team from the EOD (Explosives Ordnance Disposal) unit attended and fully examined the suspicious vehicle and declared it safe.
Supt Martin Samuel, area commander for north Warwickshire, said: “We take all reports of suspicious activity and vehicles very seriously, and take whatever action is appropriate to protect people.
“On this occasion we were informed of a vehicle which had stopped at the service station to refuel and two men were seen behaving suspiciously around it.
“Following the horrific events in Woolwich on Wednesday everyone is acutely aware of the threats which some individuals pose and the harm which they are intent on causing.
“After a thorough investigation by police officers and military personnel I can confirm that the vehicle was not carrying an explosive device, as reported by some people, and the incident is now being treated as a bulk fuel theft.
“I would like to apologise to anyone who was caught up in traffic as a result of the investigation at the service station, but I am sure you will appreciate that the precaution of closing the motorway was necessary.
“Not only was it rush hour, but the start of the bank holiday weekend. It’s hard to think of a more difficult time to close the motorway.
“I would like to thank the member of the public who reported his suspicions, and everyone who has worked on this incident.”