# 22% Mileage drop after oil change **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [February 2, 2015, 3:55am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902 "2015-02-02T03:55:36Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![bengk](https://avatars.discourse-cdn.com/v4/letter/b/35a633/32.png) [@bengk](https://community.cartalk.com/u/bengk)\ **Post date:** [February 2, 2015, 3:55am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/1 "2015-02-02T03:55:36Z")
Took my 2014 Acura MDX in for scheduled oil change at 22,000 miles. For the first 22,000 miles I averaged 20.72 MPG, Immediately after the oil change the MPG dropped to 17.26, a 20% drop in MPG. Same driving habits, part city, part freeway. What could cause the significant drop in mileage after an oil change. Could the mechanic have left something disconnected, etc, etc. Puzzling. Bengk ---
**Author:** ![bengk](https://avatars.discourse-cdn.com/v4/letter/b/35a633/32.png) [@bengk](https://community.cartalk.com/u/bengk)\ **Post date:** [February 2, 2015, 3:57am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/2 "2015-02-02T03:57:55Z")
Forgot to add, I have driven over a 1000 miles since the oil change, with the average of 17.26 MPG. bengk ---
**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/30_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\ **Post date:** [February 2, 2015, 4:27am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/3 "2015-02-02T04:27:11Z")
What was the ambient temperature when you were averaging 20+ mpg, as compared to the ambient temperature now with lower mpg readings? Is the Check Engine Light lit up? Does your car call for full-synthetic motor oil? If that is the case, are you sure that the mechanic used full-synthetic? ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [February 2, 2015, 5:17am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/4 "2015-02-02T05:17:56Z")
A 2014 should have a good warranty. Just tell the place you bought it your miles per gallon is lower now. ---
**Author:** ![SteveC76](https://avatars.discourse-cdn.com/v4/letter/s/958977/32.png) [@SteveC76](https://community.cartalk.com/u/SteveC76)\ **Post date:** [February 2, 2015, 6:39am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/5 "2015-02-02T06:39:48Z")
If the check engine light has not come on yet my best guesses would be change in fuel blends, weather changes or incorrect oil. Where did you have your service work done? ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [February 2, 2015, 8:42am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/6 "2015-02-02T08:42:31Z")
I think your car calls for using 0w-20 grade of oil…Check and see if there was a mix-up at the shop and they installed an incorrect grade like maybe 15w-40 or 10w-40… ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [February 2, 2015, 8:58am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/7 "2015-02-02T08:58:46Z")
How are you measuring your gas mileage? ---
**Author:** ![galant](https://avatars.discourse-cdn.com/v4/letter/g/77aa72/32.png) [@galant](https://community.cartalk.com/u/galant)\ **Post date:** [February 2, 2015, 10:12am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/8 "2015-02-02T10:12:43Z")
Are you relying on the computer gizmo? Sometimes the mech would let the car idle for a while on the engine change bay and maybe also do a run for donuts and this could have dropped the mileage, but you mention 1000 miles and that should have improved by now. Have you looked at your receipt and also popped the hood and make sure everything is okay. Look for loose tubes, air filter box that is open and listen for hissing sounds. ---
**Author:** ![asemaster](https://avatars.discourse-cdn.com/v4/letter/a/5f9b8f/32.png) [@asemaster](https://community.cartalk.com/u/asemaster)\ **Post date:** [February 2, 2015, 10:23am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/9 "2015-02-02T10:23:49Z")
There’s a chance that they could have inadvertently reset your mpg readout when they were resetting your oil life monitor. It’s an easy honest mistake and I’ve done it myself. ---
**Author:** ![melott](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/melott/32/10827_2.png) [@melott](https://community.cartalk.com/u/melott)\ **Post date:** [February 2, 2015, 6:04pm UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/10 "2015-02-02T18:04:11Z")
I’m betting on the change in ambient temperature. Your last 1000 miles are during winter. That can make a big difference. ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [February 2, 2015, 7:02pm UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/11 "2015-02-02T19:02:20Z")
Not using e85, are you? ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [February 2, 2015, 9:15pm UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/12 "2015-02-02T21:15:53Z")
> **Not using e85, are you?** I don’t think the 2014 Acura MDX comes as a Flex Fuel vehicle. ---
**Author:** ![PvtPublic](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/pvtpublic/32/13089_2.png) [@PvtPublic](https://community.cartalk.com/u/PvtPublic)\ **Post date:** [February 2, 2015, 11:43pm UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/13 "2015-02-02T23:43:14Z")
> Not using e85, are you? > > I don’t think the 2014 Acura MDX comes as a Flex Fuel vehicle. Doesn’t mean it can’t/didn’t happen. 😉 ---
**Author:** ![rocketman](https://avatars.discourse-cdn.com/v4/letter/r/eada6e/32.png) [@rocketman](https://community.cartalk.com/u/rocketman)\ **Post date:** [February 3, 2015, 12:15am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/14 "2015-02-03T00:15:15Z")
The comments made so far are good, but for a drop over 20% I’d look for something which might have been bumped or disconnected (by mistake) during the oil change. Check the engine bay, listen for air leaks, then do the “normal” stuff . . . make cxertain that you have the proper oil (0w20), proper air pressure in your tires, nothing dragging (brakes, especially parking). Gotta be something to cause that drop. Good luck! Rocketman ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [February 3, 2015, 12:20am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/15 "2015-02-03T00:20:13Z")
> **Doesn't mean it can't/didn't happen.** Then there could be a lot more problems then just a 22% decrease in gas mileage. ---
**Author:** ![melott](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/melott/32/10827_2.png) [@melott](https://community.cartalk.com/u/melott)\ **Post date:** [February 3, 2015, 1:32am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/16 "2015-02-03T01:32:28Z")
My annual drop from summer to winter is nearly 20%. ---
**Author:** ![BustedKnuckles](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bustedknuckles/32/25_2.png) [@BustedKnuckles](https://community.cartalk.com/u/BustedKnuckles)\ **Post date:** [February 3, 2015, 5:48am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/17 "2015-02-03T05:48:50Z")
I agree with @melott. It’s most likely winter that’s doing it. A combination of cooler ambient temps and winter blend fuel. Car engines take longer to warm up, running rich until they do. ---
**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\ **Post date:** [February 3, 2015, 5:53am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/18 "2015-02-03T05:53:34Z")
+3 for winter driving. Gasoline is reformulated for winter and it is common for gas mileage to drop around 10%. ---
**Author:** ![keith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/keith/32/5518_2.png) [@keith](https://community.cartalk.com/u/keith)\ **Post date:** [February 3, 2015, 7:21am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/19 "2015-02-03T07:21:32Z")
+1 Rocketman. Maybe hey adjusted the air pressure in your tires with a defective gauge and now the tires are low. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [February 3, 2015, 9:39am UTC](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902/20 "2015-02-03T09:39:04Z")
20% is a pretty big drop. Could be winter effects, as mentioned above. If not that, the most common cause of mpg decrease – other than the owner’s measurement error – usually has something to do with the coolant temperature. Either it is too low, due to a faulty thermostat for example, or the coolant temp is ok, but the engine computer thinks it is too low, due to a faulty or unplugged engine coolant temp sensor. [Next page](https://community.cartalk.com/t/22-mileage-drop-after-oil-change/88902.md?page=2)