I've just returned from a 1000+ mile round trip pulling my caravan from Merseyside to Cornwall, Dorset and Gloucestershire and back, pulled like a dream all the way, plenty of torque etc etc. 2.2CTDI 2006 with 89k miles on. I pulled up on the drive at home and noticed a puff of smoke come from under the bonnet on the drivers side windscreen. Opened the bonnet and saw oil spewed under the bonnet, the ABS, the strut, the water reservoir and brake reservoir etc. The cap was sat 'upside down' on top of the hole it was supposed to plug ! It has snapped on the screw part and has some how flipped itself over sitting nicely bothering no one. Obviously the oil on the engine block has come out the filler hole around the upturned cap. Not a lot of oil lost at all. The question is, would an oil cap snap because of the engine being under pressure whilst towing ? Could the engine pressure cause such a problem? or have I just tightened it too much and the engine being run so long coming home (9hrs) the oil filler hole has expanded and snapped it. Bizarre circumstances. No oil warning lights, no engine overheat issues (the gauge never moved at all when towing) and no loss of power. No issues at all in fact. Weird. All theories welcomed.