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Anyone experience a drop in mpg? I had my second oil change and I am only at 12,450 miles. It seems my avg mpg dropped by about 1 -2 mpg. I had my mechanics do the oil change , very trustworthy guys not the Mazda Dealership (hate them they screw up more things than they fix)

Any comments appreciated. I also made sure my tire air pressure was good.
 

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Maybe they put the wrong viscosity oil in. Heavier weight oil will kill mpg's.
 

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Ya are you sure they put in fully synthetic? An older mechanic may have seen a economy car and just figured to throw in conventional oil, if he messed up the viscosity then he's just an idiot, it's on the oil cap right.


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Anyone experience a drop in mpg? I had my second oil change and I am only at 12,450 miles. It seems my avg mpg dropped by about 1 -2 mpg. I had my mechanics do the oil change , very trustworthy guys not the Mazda Dealership (hate them they screw up more things than they fix)

Any comments appreciated. I also made sure my tire air pressure was good.
1-2 MPG is difficult to calculate problems. Do set point A to B calculations and record your MPG and the current weather. Then calculate under the same conditions 2 oil changes later.

These cars still might be self tunning to the driver. A slow driver like myself may get things optimized for slow driving. And a Speedy driver might get a little more aggressive tune.
I was told I might do better racing years ago with my 1991 mustang if I kept driving aggressively, this might not be the case with todays cars.
 

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Discussion Starter #5
Finally got around to talking to my mechanic and according to my receipt they put a synthetic blend in. He said I would be fine till next oil change but that the blend probably caused the drop in mpg. I think I will get it changed at 3000miles
 

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why In the hell would someone put a synthetic blend in a car that plainly calls for full synthetic 0w-20 oil. This is why I change my oil and do maintenance myself.
 

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why In the hell would someone put a synthetic blend in a car that plainly calls for full synthetic 0w-20 oil. This is why I change my oil and do maintenance myself.
Between that, the price and the wait, I've never understood not doing an oil change at home. Takes about 20-30 minutes and it's usually less expensive. Plus, you never have to worry about what kind of oil or filter is used. It's a great opportunity to check all your fluids, filters and clean out any dirt, leaves, etc that have accumulated under the hood as well.
 
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Between that, the price and the wait, I've never understood not doing an oil change at home. Takes about 20-30 minutes and it's usually less expensive. Plus, you never have to worry about what kind of oil or filter is used. It's a great opportunity to check all your fluids, filters and clean out any dirt, leaves, etc that have accumulated under the hood as well.
I actually used to do all my own oil changes until I got my 07 Mazda 3. I found out they used a cartridge or something? Note I am not a mechanically inclined guy but I wasn't sure so I let them do it. Is it any harder to change than it used to be? Other reason I think I stopped was having to dispose of the old oil became a pain. I trust the guys that work on my cars they two great young guys. They probably had a helper do it which explains it though.
 

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a cartridge style filter isnt really much different instead of replacing the entire canister you just replace the filter element inside. Its very easy. Changing oil is still the same simple process it has been for a very long time. We keep the used oil in jugs to use for lubricating farm equipment but I believe you can take your old oil in to autozone and they will recycle it I dunno no one I know around here does that.
 

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Finally got around to talking to my mechanic and according to my receipt they put a synthetic blend in. He said I would be fine till next oil change but that the blend probably caused the drop in mpg. I think I will get it changed at 3000miles

Yep there's a big difference in synthetic vs synthetic blend. Blends typically contain only 10% of synthetic. At least you found the cause.


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Finally got around to talking to my mechanic and according to my receipt they put a synthetic blend in. He said I would be fine till next oil change but that the blend probably caused the drop in mpg. I think I will get it changed at 3000miles

Sounds like a "trustworthy" shop to me. I'd recommend they do it right since the manual explicitly asks for full synthetic. If this shop wants wants to keep your business, they should be able to follow the simplest instructions.
 

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Mazda's 0-20 Moly synthetic oil is one of the lightest olis at cold start , means if you drive a lot of city short distance trips on the colder engine by switching to heavier formulas even 0-20 are thicker at start so this could explain the MPG drop.... you can buy Mazda's 0-20 Moly synth online for a case of 12 bottles at around 7usd per bottle .... excellent fluid specially for colder climates and low of short distances (cold engine) driving ....
 

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Mazda's 0-20 Moly synthetic oil is one of the lightest olis at cold start , means if you drive a lot of city short distance trips on the colder engine by switching to heavier formulas even 0-20 are thicker at start so this could explain the MPG drop.... you can buy Mazda's 0-20 Moly synth online for a case of 12 bottles at around 7usd per bottle .... excellent fluid specially for colder climates and low of short distances (cold engine) driving ....

Do you have the link to purchase the oil? Thanks!




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