Why is the mileage worse after service?

Answer 1

# 1Have someone recheck the gap on the spark plugs. The plug gap being too far apart and could cause this.

# 2

sometimes the service providers use wrong engine oil, it can make 5 to 10% more consumption, or even forgot to change the oil-filter, have one case in Sacramento, the filter just after service got jam and the oil circulation stopped, - nearly spoil engine...

so choose the proper service !