Can your oil selection really affect your mpg?

[2019CRVlx]

Seems like if you chose the best (whatever that is) or the worst the difference would be insignificant.

[ September 30, 2004, 08:47 PM: Message edited by: Dan4510 ]

 

[slalom44]

I track the mileage of every tank of gas on my car. I've been doing this for years. After a while, you get a good understanding of what affects mileage. After a while, I was able to predict with amazing accuracy how good my mileage was going to be. Here are the things that I have found to have noticeable effects on mileage:

• Speed in excess of 65 mph. The faster, the worse it got.
• Windows down on the highway.
• A/C on (not as bad as windows down)
• City driving
• Really cold winter driving
• Bad headwinds on long trips
• Hard accelerations
• Different brands of tires, low tire pressure.
• Winter fuel mixture (more ethanol)
• Gas from certain gas stations
• Last but not least - heavier weight oil.

I can see a difference of about 1/2 to 1 mpg between a 10W30 and 10W40.

 

[MONKEYMAN]

When I switched to Mobil 1 5w-30 I noticed my mileage went up 1-2 mpg (Average was 25 mpg, which is what my Saturn is rated for city driving). Would usually get 23 to 24 on dino. (Castrol 5w-30). There could be other factors, but now that I am using Auto-RX and dino (SuperTech 5w-30) for the cleaning phase, mileage dropped at least 1 mpg. I know this is not scientific, but just my observation.

 

[2019CRVlx]

I imagine it would be really hard to determine if motor oil effects your mpg because no 2 tank fulls are same in terms of conditions, e.g. traffic, %city to highway mileage, etc ...

 

[blupupher]

quote:

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Originally posted by 05corollaLE:
I imagine it would be really hard to determine if motor oil effects your mpg because no 2 tank fulls are same in terms of conditions, e.g. traffic, %city to highway mileage, etc ...

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Not really. If you drive the same bit of raod all the time, you can figure out your average. I am still getting a little less mileage with the Mobil Drive clean I had put in last oil change. It was down over 2mpg, but the front tires were low on air, and it went up almost 1 mpg with that. But I am still low.

 

[Ugly3]

In my experience the only time I could tell a difference in MPG resulting from motor oil was when I had a '79 Camero. Used to run 10w30 all summer and then I would switch to synthetic 5w30 for the winter. Before the weather got cold the 5w30 synthetic would deliver maybe 2 MPG better. Never had the nerve to run 5w30 in the summer, "too thin" you know.

 

[CoosBayDave]

I wonder how you can EXACTLY fill your tank to the brim every time. I sure can't do it. For me, measuring the mileage on one tank of gas down to 1 mpg or less would be impossible.

 

[blupupher]

quote:

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Originally posted by CoosBayDave:
I wonder how you can EXACTLY fill your tank to the brim every time. I sure can't do it. For me, measuring the mileage on one tank of gas down to 1 mpg or less would be impossible.

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Why can't you do it? It may bo .1 gallons difference, but that is not enough to really make a difference. I also have one of those mileage things on my car. It is usualy within .2 or less off of what I figure manualy.

 

[javacontour]

quote:

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Originally posted by Ugly3:
Michael SR - my a/c compressor doesn't drain nearly as much as in your car

Bet you are not running a 3800 V6.

---

Nor is the Vette the same interior volume to cool.

TB

 

[Ugly3]

javacontour - Nor is the Vette the same interior volume to cool.

Just goes to show you how stupid some people can be. I have wondered why my A/C is so much more ineffieicent than other units. Never thought about the volume being cooled. Great thought Java, thanks!

 

[Shannow]

It certainly does affect mileage.

On my turbodiesel Navara, it was shipped with 10W-30 dino, and made 10.9km/l.

Switched to a 15W-40 dino HDMO, and it made just over 10.2km/l.

Last 10,000km on M1 0W-40 has been a tad over 10.8km/l.

I keep a log and an excell spreadsheet of every drop used. The mileages quoted are the average for the oil change interval, so only have one small error at the start and end of the interval (i.e. maybe 1 litre in 1000 litres)

 

[mechtech]

Automotive A.C. takes 2-5HP to run [fans included]. The energy used to run the A.C. is from fuel. There has to be a reduction in mileage.

 

[Ugly3]

slalom44 - A/C on (not as bad as windows down)

I have a 98 Chrysler Town & Country with a 3800 V6. I have the MPG meter so I can watch what is going on. The meter is quite accurate, I check it out from time to time.

Going down the hiway at 60 MPH I get ~30 MPG. I switch the A/C on and "boom" the MPG drops to ~26. Shut it off and back to ~30 MPG. I have never noticed any change in MPG with the windows up or down.

 

[Jelly]

quote:

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Originally posted by 05corollaLE:
Can your oil selection really affect your mpg?

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Yes.

 

[Michael SR]

quote:

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Originally posted by Ugly3:
Going down the hiway at 60 MPH I get ~30 MPG. I switch the A/C on and "boom" the MPG drops to ~26. Shut it off and back to ~30 MPG. I have never noticed any change in MPG with the windows up or down.

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i have a meter in my vette, too. i was surprised to see no difference with windows open and/or headlights up. my a/c compressor doesn't drain nearly as much as in your car, though, i only get a ~1mpg drop.

-michael

 

[Ugly3]

Michael SR - my a/c compressor doesn't drain nearly as much as in your car

Bet you are not running a 3800 V6.

 

[Ugly3]

I had a 1962 Chevy wagon with an inline 6 (maybe 230 cube) and added an aftermarket A/C unit. The thing would freeze you out of the wagon and the MPG never changed. Always got 19.5 MPG on the hiway no matter what.

 

[Shannow]

mechtech,
assuming the engine is providing all of that energy, you're right, and it should be about an extra litre per hour. Maybe a quarter to 1/3 of that energy comes from additional engine braking when you are throttle off over-run, descnding hills etc.

 

[Patman]

On my C5 Corvette I see my instant MPG go up or down by about 2-3 MPG when I turn the AC on or off.

 

[rjundi]

quote:

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Originally posted by 05corollaLE:
Seems like if you chose the best (whatever that is) or the worst the difference would be insignificant.

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I agree and I personally think the difference will be 0-2MPG +/- which is very insignificant on a car that easily can achieve 30MPG+. The biggest factor on old car was never oil whic was anything from blend 20W-50 (wrong) to 0W-30 Mobil 1(I believe). It was the winter vs summer seasons. Obviously better in the summer.