I got my first oil change and it was free from my dealer. After they changed my oil, my gas mileage has gone down. I was getting 19 to 19.5 mpg on my readout and now I am only getting 18 to 18.5. Anyone else had the same thing happen to their Z?

 

... b/c the more miles you put into a car, the older the engine gets. breaking down. and i dont think that it really do anything to the car. i think that you're just exaggerting. maybe you're just driving differently as you used to. IDK!!!

 

19-18?! You must have an automatic trans.

 

My car is at 20K miles and I'm getting 19.7....before JWT pop charger was installed I was getiing 19.5.

 

I noticed the same drop in mpg after my first oil change. I am not driving any different than I was before. I did notice on the oil change sticker that they used regular castrol oil instead of synthetic oil. Could this lead to the lesser mpg?

 

I had my oil changed at 200 miles, 1000 miles and again at 2100 miles (for break-in purposes). I don't baby my car by any means...

I get 20.5 to 21 mpg city/hwy combined and I have averaged over 20 mpg since the beginning. And for what its worth, the Infinity dealership where I get it serviced uses the Castrol as well..

 

After my latest mod, my 6MT is up to 26.7 MPG (I drive a LOT of highway driving... Average spped about 75 - 80 MPH)

Other than the general expenses of tires / brakes / oil changes, I save money driving the Z to work with better gas milage than I do with my Jeep Cherokee and Regular Unleaded.