High mileage oil ruined gas mileage?

[geeman789]

Originally Posted by kschachn
Originally Posted by geeman789
They are an excellent way for the oil maker to generate additional profit. Add a few pennies to the cost, and charge a few dollars more for the oil ... !

Here in the Milwaukee area at least, at Walmart they are the same price as the non HM products. For example, M1 5W-30 and 5W-30 HM are both $25.47 for 5 quarts.


Hmmm ... the M1 HM does appear to be the same price here as well, as is PP HM. All the conventional HM oils are more expensive though ... not sure what the difference is.

 

[Rollo]

Wow...it is hard to disregard so may folks on here saying it has nothing to do with the oil but the car has been at the dealership multiple times since then and they noticed no problems with it. I have no lights on in the dash and we have changed air filters as well.

This was a mistake made by me, who put the oil in without paying attention to exactly what oil I was using and my wife who just picked up the wrong thing by accident.

The change in mileage exactly coincided with the oil change but I will swing by an auto parts store to get a scan in case there is something that is being ignored by the dealer. I will report back when I find more information.

I have lurked on this forum from time to time over the years to absorb some of the expertise available. If you guys are certain it wasn't the oil I will continue to look elsewhere. Thanks!

 

[ekpolk]

You didn't even offer what viscosities are involved. What had been in before, that of this HM oil, and what you followed up with. This dramatic a change shouldn't be oil-involved anyway, but still, you'd need way more particulars before anyone could begin to offer meaningful information.

 

[Rollo]

Originally Posted by ekpolk
You didn't even offer what viscosities are involved. What had been in before, that of this HM oil, and what you followed up with. This dramatic a change shouldn't be oil-involved anyway, but still, you'd need way more particulars before anyone could begin to offer meaningful information.


I used 0w20 Pennzoil ultra platinum or 0w20 Mobil 1 full synthetic for all oil changes not completed by the dealer. The one with the high mileage oil was also 0w20. I don't remember the exact sequence of which I used when, I just purchased the one on sale. I changed the filter each time and as I said I did not wait the normal OCI after the gas mileage change--I changed it out again and then again during a short time because I assumed the problem was related to the high mileage oil additives.

My normal OCI is 5k miles.

thanks...

 

[Triple_Se7en]

Originally Posted by Rollo
My wife has a 2015 Subaru Forester we purchased used in 2016 with about 11k miles on it. The first few oil changes were either completed at a Subaru dealer or by an oil change service using Pennzoil Ultra Platinum. I eventually began completing the oil changes myself using either Mobil 1 or Pennzoil full synthetic.


The answer to your problem is right inside your opening first sentence. You bought a used vehicle in 2016 and three years later, it still only has 11K miles on it. So is it possible that your wife has only put 6-7K in mileage these past three years? Does she drive slow, like city driving 25-35MPH and never hammers the gas pedal, to get fuel moving more rapidly?

Buy top-tier gas and get those fuel injectors cleaned. They are probably gumming-up. Then take that vehicle on the freeway every few weeks and floor the gas pedal a few times.

But do it safely and in light traffic..... nobody in any lanes next to you. Or, swap vehicles once a week. Drive hers and she gets to drive yours once a week. Put some miles on that barely used vehicle.

 

[kstanf150]

I'm surprised a post like this is still alive
HM oil didn't cause his problem . Period

 

[Colt45ws]

I should ask, is this a real calculated miles divided by gallons used type MPG or is a gauge in the car type MPG?
Originally Posted by Triple_Se7en
Originally Posted by Rollo
My wife has a 2015 Subaru Forester we purchased used in 2016 with about 11k miles on it. The first few oil changes were either completed at a Subaru dealer or by an oil change service using Pennzoil Ultra Platinum. I eventually began completing the oil changes myself using either Mobil 1 or Pennzoil full synthetic.


The answer to your problem is right inside your opening first sentence. You bought a used vehicle in 2016 and three years later, it still only has 11K miles on it. So is it possible that your wife has only put 6-7K in mileage these past three years? Does she drive slow, like city driving 25-35MPH and never hammers the gas pedal, to get fuel moving more rapidly?

Buy top-tier gas and get those fuel injectors cleaned. They are probably gumming-up. Then take that vehicle on the freeway every few weeks and floor the gas pedal a few times.

But do it safely and in light traffic..... nobody in any lanes next to you. Or, swap vehicles once a week. Drive hers and she gets to drive yours once a week. Put some miles on that barely used vehicle.


The way it reads to me they bought it a year old with 11k miles on it, but I could be wrong.

 

[Rollo]

Originally Posted by Colt45ws
I should ask, is this a real calculated miles divided by gallons used type MPG or is a gauge in the car type MPG?
Originally Posted by Triple_Se7en
Originally Posted by Rollo
My wife has a 2015 Subaru Forester we purchased used in 2016 with about 11k miles on it. The first few oil changes were either completed at a Subaru dealer or by an oil change service using Pennzoil Ultra Platinum. I eventually began completing the oil changes myself using either Mobil 1 or Pennzoil full synthetic.


The answer to your problem is right inside your opening first sentence. You bought a used vehicle in 2016 and three years later, it still only has 11K miles on it. So is it possible that your wife has only put 6-7K in mileage these past three years? Does she drive slow, like city driving 25-35MPH and never hammers the gas pedal, to get fuel moving more rapidly?

Buy top-tier gas and get those fuel injectors cleaned. They are probably gumming-up. Then take that vehicle on the freeway every few weeks and floor the gas pedal a few times.

But do it safely and in light traffic..... nobody in any lanes next to you. Or, swap vehicles once a week. Drive hers and she gets to drive yours once a week. Put some miles on that barely used vehicle.


The way it reads to me they bought it a year old with 11k miles on it, but I could be wrong.


Right. The vehicle now has 66000 miles on it. It had 11k on it when purchased in January of 2016.

I appreciate the responses and as I said, I will look elsewhere for the problem. thanks again...

 

[The Critic]

Has the car received a new set of tires at any point during your ownership?

 

[bbhero]

Originally Posted by JohnnyJohnson
Originally Posted by Blkstanger
It's not the oil. Look elsewhere.


This

Yeah I totally agree ^^^^^^

 

[RyanY]

Originally Posted by bbhero
Originally Posted by JohnnyJohnson
Originally Posted by Blkstanger
It's not the oil. Look elsewhere.


This

Yeah I totally agree ^^^^^^



^this
Some other things to start with (but not all possible causes):

Fuel injectors (dump a can of Techron or Berryman in the tank at next fillup)
Brakes dragging
Different brand of gas
Your wife drives like mine does (at least 5 MPG difference from me)
Fuel system leak
Etc.

 

[SirTanon]

Something else to consider...

OP, in your initial post, you mentioned:
Originally Posted by Rollo
The first few oil changes were either completed at a Subaru dealer or by an oil change service using Pennzoil Ultra Platinum. I eventually began completing the oil changes myself using either Mobil 1 or Pennzoil full synthetic.

When you bring your car to the dealer for changes, they will also do things like checking the air filter, tire pressure, brakes, plugs, etc.. When you start doing your own oil changes in lieu of the dealership, a lot of that extra stuff gets ignored or overlooked. I know because I've done it myself from time to time..

.. Are you checking all those other things? If not, then it stands to reason that the air filter might be getting loaded up and thus restricting airflow (which will cause MPG to drop), etc.. something (or multiple things) that the dealer might have otherwise serviced during their oil change regimen, might be in dire need of servicing, and thus be behind the drop in MPG your wife is experiencing.