a few things..

[Fulltiltorgasm]

noticed lately fuel economy is becoming slightly worse.. im guessing this mite have to do with the 02 sensor engines done 100,000 prob due for a change.. other question check engine coolant first time in a while ie 4 months or when last serviced.. had to fill it up with about 400ml of water.. im not sure wether my mechanic checks it and fills it up every service (5000km) wondering does this seem like a little to much loss of coolant or about rite?? how much coolant is in the engine a few litres or so?? cheers

[vipfto]

it takes about 6l of water

yip O2 sensor will be good place to start

I would jut keep an eye on water levels for now over time 400ml is ok but if weekly or daily you may have a prob

[Fulltiltorgasm]

cheers... yeah thinking about it last night prob been closer to 6 months since its been serviced and always check all oils just neglected checking coolant lately filled it up and will keep a keen on eye on it