2016 CX-5 - Lower Gas Mileage after Oil and Filter Change

[devo1255]

Up until my last oil change, I let the dealership do all the servicing. Since the local dealer shut down, and I do my own oil changes to my older Mazda 3, I was ready to start my own changes on my CX-5.

However, I am noticing that my gas mileage has decreased somewhat right after the oil change and I'm scratching my head. The following are some details and hoping you knowledgeable folks can come up with some possible reasons I am experiencing this:

Previous oil changes from Mazda Dealership:
Oil: Mazda Branded 0W20 Full Synthetic (MZDSYN0W20BK)
Filter: Mazda Filter PE01-14-302A-MV

Last Oil change (First time doing it myself):
Oil: Idemitsu 0W20 Full Synthetic
Filter: Mazda Filter 1WPE-14-302

Notes:
- I chose the Idemitsu oil based on reading that it is most close to Mazda Branded on the market and the filter is a direct superseded part for my car.
- I did have to use all 5 quarts since the oil was on the lower end of the dip stick after the change and warming up.
- The filter did look slightly smaller than the one I replaced, but not by much and installed with no issues. No other items were changed/replaced on that car (like air filters).
- Been driving the car for about 500 miles after the oil change. No leaks observed.
- Previous MPG: 28-30, Current MPG: 24-26
- No change in driving habits/routes.
- Tires still holding recommended pressures.
- Been using Costco gas from same station for the past 3 years.

All insights are appreciated. Particularly interested in those that have switched to the filter I am using and knowing their experience.

 

[HyFlyer]

... Previous MPG: 28-30, Current MPG: 24-26 ...

Was previous during warmer months and current is now cold climate operations? That'll make a difference . I don't see the oil change making a difference at all.

 

[devo1255]

Was previous during warmer months and current is now cold climate operations? That'll make a difference . I don't see the oil change making a difference at all.

Good point.

Same climate. I live in Southern California where the weather is relatively constant all year long.

 

[ApeScxit]

I went from around 30 psi to 37 and it seems I’m getting better mileage 25.7 to 28.5. I wonder if they messed with your tire pressure.

 

[ColtX-5]

Its almost impossible for oil the affect fuel mileage enough to see at the pump. Most likely it is route, fuel formulation or octane. Did you check your tire pressure?

 

[Odrapnew]

Its almost impossible for oil the affect fuel mileage enough to see at the pump. Most likely it is route, fuel formulation or octane. Did you check your tire pressure?

I agree.
About the only way it would make a noticeable difference is if the weight was changed and to see a 4mpg change, would probably have to be a big hot temp weight change (i.e. going to a 0W40).

 

[yrwei52]

⋯ Previous oil changes from Mazda Dealership:
Oil: Mazda Branded 0W20 Full Synthetic (MZDSYN0W20BK)
Filter: Mazda Filter PE01-14-302A-MV

MZDSYN0W20BK is a generic Mazda part number for bulk 0W-20 full synthetic oil. It can be any brand of bulk oil the Mazda dealer could find with lowest possible cost. And PE01-14-302A-MV is one of the “Value Product” maintenance parts Mazda North American Operations offer for lower price to the dealerships and customers. The “value” oil filter is made in Mexico, and the quality seems to be lower than standard Mazda parts but they still meet the OEM standard.

Last Oil change (First time doing it myself):
Oil: Idemitsu 0W20 Full Synthetic
Filter: Mazda Filter 1WPE-14-302

Is the Idemitsu 0W-20 full synthetic oil you use the latest SP / GF-6 oil? 1WPE-14-302 is the Mazda “standard” OEM oil filter with better quality and higher price than cheaper “value” oil filter Mazda dealers are using for their oil change. 1WPE-14-302 is made in Thailand by Denso.

Notes:
- I chose the Idemitsu oil based on reading that it is most close to Mazda Branded on the market and the filter is a direct superseded part for my car.

Current Idemitsu 0W-20 SP / GF-6 oil is different from Mazda 0W-20 moly oil if that is what you meant the “Mazda branded” oil. Your dealer didn’t use Mazda moly oil as the part number for moly oil is 0000-G5-0W20-MQ.

- I did have to use all 5 quarts since the oil was on the lower end of the dip stick after the change and warming up.

Actually the 2.5L NA requires 5.25 quarts of oil to make the oil level reaching the Full mark of the dipstick, even though the manual says 4.8 quarts. I check the oil level the first thing in the morning before the engine start for easy to see the oil level on the dipstick. I’ve done the experiment that the difference between warm and cold for oil level is very minimum.

- The filter did look slightly smaller than the one I replaced, but not by much and installed with no issues. No other items were changed/replaced on that car (like air filters).

Yes current Thai made “standard” OEM 1WPE-14-302 oil filter with size 65 mm / 14 flutes is a bit smaller than previous Japanese made “standard” OEM PE01-14-302A oil filter and Mexican made “value” PE01-14-302A-MV oil filter with size 67 mm / 14 flutes.

- Been driving the car for about 500 miles after the oil change. No leaks observed.
- Previous MPG: 28-30, Current MPG: 24-26
- No change in driving habits/routes.
- Tires still holding recommended pressures.

Are the mpg numbers from onboard computer calculation or gas pump calculation?

- Been using Costco gas from same station for the past 3 years.

Sometimes the particular gas pump may give you inaccurate amount of gas due to the lack of calibration. If you use gas pump calculation to get the mpg numbers, you may try a different gas pump at the same Costco station next time and see.

All insights are appreciated. Particularly interested in those that have switched to the filter I am using and knowing their experience.

As many have said before, it’s higher unlikely changing the oil with different oil and oil filter would affect gas mileage with such significant numbers. Something else has happened.