I have three 2005 MCS between 30k and 100k miles on the motor, and all are well maintained. Gas consumption depends on driving style and weather, but they all are in the same ballpark for the same type of driving. Local short stints, lots of cold starts and no real stretch-your-legs runs and I will see low 20s. Freeway cruising at 70/75 without a headwind is 30-32mpg. I run Royal Purple Synchromax in all gearboxes, but even before I put that in, MPGs were in that ballpark. Clean your air filters, put enough air into the tires and synthetic vs dino oil should not make much of a difference.

 

Swapped out the upstream o2 sensor this morning... time to fill it up and hope for the best!

 

Looks cleaner than the ones in my manifold right now!!

What brand did you end up going with? How much did they cost, if you don't mind me asking? I've been thinking that mine might be going soon. I couldn't find OEM for less than $150 anywhere. But I did find some aftermarket cheapo ones that I was advised to stay away from, that I'm very tempted to try one day.

I don't think I've ever had more than 20 city. I can get 25 hwy by going less than 70 and being on cruise control...but ain't nobody have time for that! My average when cruising around college town is usually in the 18's.

Best way to check wheel bearings is to jiggle the wheel with the car in the air. Shouldn't have any play along the mounting plane.

 

I am going to wager that the shiny O2 sensor likely make no difference.

 

I'm only 150 miles in but it seems to be making a noticeable difference. The car computer (yes, its not entirely accurate) is reading 25-26 mpg's versus the 18-20 i used to see. My driving routes have not changed (did this exact trip last weekend, with the same gas from the same gas station). After driving 150 miles i'm in between half tank and 3/4's. Last fill up i was at half tank around 100-120 miles!

Honestly it seems i gained a lot of mpgs on highway miles. Local MPG still doesn't look too good and thats understandable given city driving is a red light at every block, but definitely getting better than i was before on highway driving.

Going to track fill up's for the next few weeks and hoping this improvement continues...


I used a NTK sensor off amazon that was about $100 and a direct fit. The one that came out of the car also had "NTK" inscribed on it. Don't think the previous owner ever replaced the O2 sensors as he kept immaculate service/maintenance records and this wasn't on the list. Wondering if NTK makes the OEM sensor?