2004 Town Car mileage drop of 2 MPG
2 MPG drop isn't much, but ..... why? Note: No codes.
I am not actively looking to resolve this until codes are received.
But, other Town Car owners are encouraged to reply.
2004 Town Car with 102,000 miles and NO oil added between 5,000 mile
changes. I.E., cannot come up with a good reason to buy another car.
City driving went from 19 to 17. (I know, not bad for 4.6 power)
Highway went from 26 at 75 mph average to 25 at 65 mph average.
Began Approximately after getting 2 new tires + alignment.
Prior to that, replaced plugs and coils as preventive maintenance
with no affect on gas mileage.
Air filter is slightly dirty. Tire pressures checked regularly.
Previous mileage obtained while using 5W20 semi-synthetic.
Moved from PA to FL and decided to use 5W30 semi-synthetic.
Anyone see that slight change of viscosity make a difference?
Personal thoughts include O2 sensors and catalytic converter.