OCI affects MPG?

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Jimmy9190

Jimmy9190

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Just wondering here. Does anyone experience a reduction in their MPG the further you get into the OCI? I run Napa brand 10W30 in my Dodge Dakota with the 3.9 V6 engine, and I use a ProSelect filter. It just turned over 117,000 miles on the odometer and is in great shape otherwise.

I seem to notice that the closer I get to about 2800 to 3000 miles in my OCI the MPG always dips down 2 or 3 miles a gallon. Power seems a bit off too but nothing to worry about. I wonder if this is an effect from shearing or some other property of motor oil that the guru's here will know more about.

I appreciate any help/info you have.
 
I change around 5-8k and I seem to stay pretty close to the same MPG within the OCI but durning the winter, there is a SLIGHT (within the noise) improvement towards the END of the OCI.

I'm talking going from 42-43 something in the winter to 41-42 something.

Take care, bill
 
I remember noticing that when I ran GC and BMW's 5w30 synthetic. I ran much longer OCIs (6000-8000 miles), but noticed the same 2 to 3 mpg drop by the end of the OCI.

The Motul synthetics I ran seemed to do the same thing, although perhaps slightly less (1-2 mpg instead of 2-3).

Motul 300V is the only oil I've run that didn't do it. It's also the most expensive. Go figure...
 
Anything is possible, maybe the oil is getting really thick toward the end of the OCI causing a drop in mpg's. Try adding a pint of MMO to the oil when you notice the drop in MPG's and see what happens.
 
When the mpg drops the oil is shot and needs to be changed. M1 EP should run farther than the oil you are running.
 
Haven't noticed this. My MPG is more dependant on my driving conditions than my OCI. If anyting my Mileage improves a few thousand into the OCI. I am pushing PP 5w20 to 10k and will keep an eye on it. My v8 ford explorer is averaging 21.5 MPG highway on this vacation trip from Farmington New Mexico to Newport beach CA and the oil only has 3k miles on it. Winter is coming so I expect a mileage drop when I drive from sea level and 80 f to 5300 feet and winter coming and lowes in the low 30's.
 
Thanks for the replies. I realize it could be the gas I use that can cause a slight drop in MPG too. I usually buy gas from BJ's Warehouse or Shell. I don't know if the gas companies have started their switch to winter gas yet, and I am not really sure if we even get winter gas here in central Florida where I live. I try to help support BJ's because my girlfriend works there. The gas station manager there said they get their gas from different suppliers, whichever one has the best price at the time each week when they buy it, but it is from a reputable name brand supplier, and sometimes it is Shell, other times it is Chevron or Cononco/Phillips. I wonder if it could be the actual gas itself.

I have been using Napa dino for over a year now, and never had any problems at all with it in my truck or in my gf's Accord. My oil looks OK, it's a bit dark in color on the dipstick but that should not matter. Hers is always a darker color too, but I always attributed that to normal oil characteristics and the fact that her car may not have seen regular oil changes before I met her. Before I started using Napa brand oil, I used Valvoline exclusively. I bought a case of Napa 10W30 for my truck and a case of their 5W20 for her Honda last month when it was on sale for $1.99 a quart, plus I got 2 free ProSelect oil filters with the purchase of the 2 cases on a local Napa coupon.

I'm close enough to my next oil change now to go ahead and change it and see if the MPG picks up. We still have some hot days here now but it will soon cool off so I won't need constant AC in my truck and that should help the MPG too.

Thanks for the help here.
 
While it doesn't happen with every oil, some do appear to increase fuel economy as you go forward. I "imagine" that it's about the time that Ford found that all those wear metals spike due to resident film disruptions.
 
Stays about the same on my current two.. actually I don't remember a car or truck it affected. Added 12-16 ounces of MMO towards the end of OCI now that helped.
 
Originally Posted By: Eric Smith
Added 12-16 ounces of MMO towards the end of OCI now that helped.


It works, and is certainly worth a try if the oil is only lasting ~3000 miles.
 
Originally Posted By: Eric Smith
Stays about the same on my current two.. actually I don't remember a car or truck it affected. Added 12-16 ounces of MMO towards the end of OCI now that helped.


I really haven't ever noticed any change to MPG towards the end of an OCI in many of the vehicles I've owned either. And my Ion I've been going by the OLM, which has been around 7-7500 mile OCI's and the MPG's usually are pretty solid throughout. The only major factor I ever notice changes in MPG with this car are changes in temperatures. winter's suck and is the only times I get less than 30 MPG. Hot summer days are the best when I reach over 35 MPG.

usually toward the end of my OCI, like 500 miles or so, I'll drop about 8 or so ounces of MMO in the oil just as a little clean up effort hopefully to keep any kinds of [censored] from sticking around.
 
There are so many factors that effect MPG that I doubt it is the oil. To name a few:

1. vehicle load
2. tire pressure
3. ambient air temp & humidity
4. age & quality of fuel
5. measurement technique (how exact)
6. driving style
7. number of traffic lights & traffic jams
 
Originally Posted By: PT1
There are so many factors that effect MPG that I doubt it is the oil. To name a few:

1. vehicle load
2. tire pressure
3. ambient air temp & humidity
4. age & quality of fuel
5. measurement technique (how exact)
6. driving style
7. number of traffic lights & traffic jams


transmission also a factor, with a stick shift netting better than an automatic. Tire pressure and ambient temperatures are huge factors.
 
Just change it out at 2800 each time with that oil in your vehicle. Some oils would go a little farther,but as long as you change it about 2800 it's no big deal.
 
Originally Posted By: Jimmy9190
Thanks for the replies. I realize it could be the gas I use that can cause a slight drop in MPG too. I usually buy gas from BJ's Warehouse or Shell. I don't know if the gas companies have started their switch to winter gas yet, and I am not really sure if we even get winter gas here in central Florida where I live. I try to help support BJ's because my girlfriend works there. The gas station manager there said they get their gas from different suppliers, whichever one has the best price at the time each week when they buy it, but it is from a reputable name brand supplier, and sometimes it is Shell, other times it is Chevron or Cononco/Phillips. I wonder if it could be the actual gas itself.

I have been using Napa dino for over a year now, and never had any problems at all with it in my truck or in my gf's Accord. My oil looks OK, it's a bit dark in color on the dipstick but that should not matter. Hers is always a darker color too, but I always attributed that to normal oil characteristics and the fact that her car may not have seen regular oil changes before I met her. Before I started using Napa brand oil, I used Valvoline exclusively. I bought a case of Napa 10W30 for my truck and a case of their 5W20 for her Honda last month when it was on sale for $1.99 a quart, plus I got 2 free ProSelect oil filters with the purchase of the 2 cases on a local Napa coupon.

I'm close enough to my next oil change now to go ahead and change it and see if the MPG picks up. We still have some hot days here now but it will soon cool off so I won't need constant AC in my truck and that should help the MPG too.

Thanks for the help here.
I ran Auto RX in my 3.9 and it really cleaned up the ring packs. My MPG went up big time. Might want to try it.
 
Oil will shear and thin out before it thickens.
It's hard to believe that at 2,800 miles the oil is thickened.
Gas mileage should go up a bit because of probable slight thinning at those low miles.
 
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