hey guys, just wanted to get some advice on my patrol, the gas consumtion has never been great but at the moment im only getting 310km from a 90lt tank and when im towing my van (17ft gvm 1500kg) its dropping to around the 270km range. its getting too the point i cant afford to drive it! i have changed the air filter and plugs, that hasnt done anything had i checked by a mechanic he couldnt find anything. next option is valve clearances will that change the consumtion? anything else i should be checking?