imo,the most important thing to do is change the oil and filter. going by a thread on here about changing the fuel filter (seatkids opinion)and the 1 i went with,why change it every year? dont forget its now getting colder so no doubt if its working then your booster heater may have started kicking in and this will use a bit more fuel. i too can only get 35-40 mpg round town,but have had it up to 59 mpg on a motorway @65 mph. the link saif gave is the seller i bought my oil extractor from,even though it took me an age to do the oil change,think that was more to do with confidence then anything else,i did seem to get the same ammount of oil out as what i ended up putting in. point to remember if you do get 1 make sure you unravel the pipes 1st before using or as like me your be sucking a lot of bloody air out lol and no oil.