--- title: Fuel Economy Dropped: The Maintenance Causes url: https://xpressoilandlube.com/problems/poor-fuel-economy/ business: Xpress Oil & Lube (Xpress Oil & Lube Center) shops: Reno Northwest: 6100 Mae Anne Ave, Reno, NV 89523, (775) 787-1000, Mon-Fri 8 am-5 pm, Sat 8 am-4 pm, Sun closed; Reno South: 4993 Longley Ln, Reno, NV 89502, (775) 828-6996, Mon-Fri 8 am-5 pm, Sat 8 am-3 pm, Sun closed; Carson City: 1861 E College Pkwy, Carson City, NV 89706, (775) 883-5823, Mon-Fri 8 am-5 pm, Sat 8 am-4 pm, Sun closed; Gardnerville: 1293 US Hwy 395 N, Gardnerville, NV 89410, (775) 301-5912, Mon-Fri 9 am-5 pm, Sat 9 am-3 pm, Sun closed type: Drive-in oil change and vehicle maintenance, no appointment needed, since 1983 --- Today's coupons - $10 off full-service oil change - $5 off smog check - $25 off transmission fluid service [See all coupons](https://xpressoilandlube.com/coupons/) - [Home](https://xpressoilandlube.com/) - [Problems](https://xpressoilandlube.com/problems/) - Fuel economy dropped # My fuel economy dropped. What changed? A drop in fuel economy with no change in your driving usually comes from maintenance: underinflated tires, a clogged engine air filter, oil of the wrong grade or a fuel system full of deposits. Each is small on its own, each is something we check in the bay, and together they explain most of the mileage people lose. ★★★★★ 4.7 stars from 952 Google reviews At your next visit General guidance for this symptom. A warning light that is flashing or an overheating engine: stop driving and call. ## Likely causes - Low tire pressure Tires lose pressure as the weather cools, roughly a pound for every 10 F drop, and a Reno October that goes from 80 F afternoons to 30 F mornings takes several pounds out of them. Fueleconomy.gov puts the cost of underinflation at about 0.2 percent per pound below spec and says proper inflation can improve mileage by up to 3 percent. We set pressures to the door-jamb label at every service. [Multi-point maintenance check](https://xpressoilandlube.com/services/maintenance-check/) - A clogged engine air filter On older carbureted engines a dirty filter cost real mileage; on modern fuel-injected engines fueleconomy.gov says it mostly costs acceleration, not economy. It still matters for how the car feels and for emissions, and in the high desert it clogs fast. We replace it when daylight will not pass through. [Engine air filter](https://xpressoilandlube.com/services/engine-air-filter/) - The wrong oil grade Fueleconomy.gov says using the manufacturer's recommended grade of motor oil can improve mileage by 1 to 2 percent, and that a heavier oil than specified can cost about that much. If the last service center put 10W-30 in a 0W-20 engine, the next oil change with the right grade is the fix. [Full-service oil change](https://xpressoilandlube.com/services/oil-change/) - Deposits in the fuel system Injectors that dribble instead of mist and a carboned intake burn fuel badly. A fuel system cleaning clears deposits and is worth doing before anyone chases sensors. On a car that hesitates as well as drinking, it is the first thing we suggest. [Fuel system cleaning](https://xpressoilandlube.com/services/fuel-system-cleaning/) - A failing oxygen sensor or a dragging brake Fueleconomy.gov notes that fixing a serious maintenance problem such as a faulty oxygen sensor can improve mileage by as much as 40 percent. A brake caliper that does not release costs mileage and makes a wheel hot. Both are repair-shop items. We can tell you if a wheel is hot after a drive and whether the check engine light has a code behind it. [Multi-point maintenance check](https://xpressoilandlube.com/services/maintenance-check/) Nobody notices a mile per gallon. People notice when the tank that used to get them from Gardnerville to Reno and back twice now does it once and a half. Fuel economy is one of the most honest readouts a car has, because it adds up everything: tires, air, oil, fuel delivery, temperature, and how the car is driven. The federal fueleconomy.gov site publishes what each maintenance item is worth, and the numbers are useful because they tell you what to fix first. ## First, rule out the things that are not the car - Winter blend gasoline, sold from roughly October to spring, carries less energy per gallon; fueleconomy.gov says cold weather alone can cut short-trip mileage sharply - A roof box for ski season: fueleconomy.gov puts a large roof cargo box at up to a 25 percent penalty at highway speed - A/C in July, which is a real load on a small engine at Reno's 90 F afternoons - A new commute with more stop lights, or a new driver in the household - Carrying the snowboards, the tools and the dog bed all year If none of those changed and the mileage still fell, the car is telling you something, and the bay check is where to start. ## What we check and set Tire pressure to the placard on the door jamb, cold. Engine air filter, held up to the light. Oil grade on the cap against what the last sticker says went in, and the oil's condition on the stick. Fuel cap seal. A look at the fuel system history, and a [fuel system cleaning](https://xpressoilandlube.com/services/fuel-system-cleaning/) if the car has never had one or is hesitating. All of that happens during a [full-service oil change](https://xpressoilandlube.com/services/oil-change/) at Mae Anne Avenue, Longley Lane, College Parkway or US 395, and the invoice lists what we found. Oxygen sensors, thermostats stuck open (an engine that never warms up burns more fuel), dragging brakes and transmission problems go to a repair shop. We tell you which of those we suspect and why. ## Altitude and the number on the window sticker The EPA mileage on the window sticker was measured at sea level. At 4,500 feet the engine makes less power per stroke, the computer adjusts, and on most modern engines the economy is close to the sticker on flat roads and worse on grades. The Mount Rose Highway from Reno climbs almost 4,000 feet, and a Subaru that does 30 mpg on I-80 does nowhere near that on the way up. That is not a problem to fix; it is the hill. Track your mileage on the same route for a fair comparison. ## Keeping the number up The cheapest fuel economy in Northern Nevada is maintenance on the manual's schedule: the right oil at the manual's interval, a filter that gets looked at every oil change because of the dust, tire pressure checked monthly through the fall temperature drop, and a fuel system cleaning every so often on a car that lives on short trips. Our [between-oil-changes checklist](https://xpressoilandlube.com/checklists/between-oil-changes/) turns that into a monthly habit. ### Sources - [fueleconomy.gov/feg/maintain.jsp](https://www.fueleconomy.gov/feg/maintain.jsp) (US DOE / EPA fueleconomy.gov: tire pressure, oil grade, air filter and oxygen sensor effects on fuel economy; read 10/15/26) - [fueleconomy.gov/feg/coldweather.shtml](https://www.fueleconomy.gov/feg/coldweather.shtml) (fueleconomy.gov: cold weather and winter fuel effects on mileage; read 10/15/26) - [nhtsa.gov/vehicle-safety/tires](https://www.nhtsa.gov/vehicle-safety/tires) (NHTSA: check tire pressure monthly against the vehicle placard; read 10/15/26) ### Your service center: Reno Northwest - Call [(775) 787-1000](tel:+17757871000) Mon-Fri 8 am-5 pm, Sat 8 am-4 pm, Sun closed - Address 6100 Mae Anne Ave, Reno, NV 89523 [Directions](https://www.google.com/maps/dir/?api=1&destination=6100+Mae+Anne+Ave%2C+Reno%2C+NV+89523&destination_place_id=ChIJ3dFA7yBEmYARYg1CtQTi_Bk) ### Related - [Rough idle or hesitation](https://xpressoilandlube.com/problems/rough-idle-or-hesitation/) - [Fuel system cleaning](https://xpressoilandlube.com/services/fuel-system-cleaning/) - [Engine air filter](https://xpressoilandlube.com/services/engine-air-filter/) - [High altitude, mountain passes and your engine](https://xpressoilandlube.com/guides/high-altitude-driving-maintenance/) - [Reading the oil cap: viscosity grades like 0W-20 and 5W-30](https://xpressoilandlube.com/guides/reading-your-oil-cap/) - [Between oil changes: a monthly five-minute check](https://xpressoilandlube.com/checklists/between-oil-changes/) Drive in. No appointment. Drive out. Locally owned in Northern Nevada since 1983. No appointment, no pressure: we tell you what the inspection found and you decide. [About us](https://xpressoilandlube.com/about/) ## What we do about it [### Multi-point maintenance check Learn more](https://xpressoilandlube.com/services/maintenance-check/)[### Engine air filter Learn more](https://xpressoilandlube.com/services/engine-air-filter/)[### Full-service oil change Learn more](https://xpressoilandlube.com/services/oil-change/)[### Fuel system cleaning Learn more](https://xpressoilandlube.com/services/fuel-system-cleaning/) ## Questions people ask Still have a question? Call your service center or drive in; there is no appointment to make. ### How much does a dirty air filter cost in mileage? On a modern fuel-injected engine, little; fueleconomy.gov says it hurts acceleration more than economy. On older carbureted engines it was significant. We replace it for the engine's sake either way. ### Will a fuel system cleaning improve my mileage? When deposits are the cause, it helps, and the hesitation goes with it. It will not fix an oxygen sensor or a dragging brake, and we will tell you if those look more likely. ### Is synthetic oil better for fuel economy? The grade matters more than the type. A full synthetic in the manual's grade flows better cold and holds its viscosity hot, which helps a little on a Reno winter morning. The 1 to 2 percent figure from fueleconomy.gov is about using the correct grade. ### My truck's mileage fell after I put bigger tires on it. Why? Bigger tires change the gearing and the rolling resistance, and the odometer now under-counts miles, which makes the calculated mileage look worse than it is. A repair shop or the dealer can correct the speedometer calibration.