2002 Suburban gas mileage dropping

[jstiene]

Hi..I have a 2002 Suburban with 198K miles on it. I am the original owner and not very mechanically inclined in terms of cars. I drive 120 miles/day back and forth to work all highway. My mileage is averaging around 15-16. Is this normal for a vehicle of this age and high mileage? And is there anything I can do to improve it? I have seen some posts regarding Seafoam but just wanted to see what the latest suggestions are.

also, does it hurt to slightly overinflate my tires? I do check them regularly btw to make sure they are at proper inflation.

[vncj96]

What kind of miles are those, are you hitting traffic jams on the highway, I would think that 120miles a day even with 200k on the clock it would be higher, on my old 99 I can pull 18 when just doing a straight shot on the highway. Tune-up time? Go by what the tire manufacturer says on the sidewall of the tire for proper inflation

[jstiene]

They are 95% highway miles...straight shot up and down i75...which is why I wonder what my issue is...it has been about 60K or so since my last tuneup..I guess I am due..maybe start there..

[Tdaz250]

A tune could help your mileage if you feel like going that route. Or an air intake. Intake helped my mileage.

[roger97338]

Use a K&N air filter. Also, switch to a fully synthetic motor oil.

[JennaBear]

Have you replaced your fuel filter and fuel pump? I would also look into your spark plugs and clean out your MAF and throttle body. If you have a few mins, a Seafoam session could do some good as well.