oil change killed my MPG.

[beef5stew]

This one has be puzzled. When I bought my Pilot, the local Jiffy Lube did not carry 0w oil, so they used 5w with no issues. I was getting a consistent 22-24 mpg.

They now carry 0w oil, so I had them use that. I now can't get an MPG higher than 18MPG.

What the heck?

[RinconVTR]

Not related to oil...

But if you think it is, then change back to the 5w-20 (or was it 5w-30?) they used before???

[Strate L O S S]

with 6mpg it pays to go purchase another jiffy lube oil change within one tank of fuel.

that's assuming your mpg goes back up which I highly doubt that it will.


Sent from AutoGuide.com Free App

[bblueser]

See Above

[rocky]

Did they forget to put more in?


Sent from AutoGuide.com App

[humanoid]

OP how sure are you that they put in 5-30 or 5-20?

[road2cycle]

Is it possible they forgot to drain the old oil before putting new oil in? I'd check your dipstick to rule that out.

[whizmo]

Don't bark up the wrong tree. The change in mileage with a change in oil is coincidence. Something else has changed. I'd gather data over a couple months before starting to look for a problem.

- Mark

[Yahooligan]

Jiffy Lube isn't known for their quality work, before driving any further I would definitely pull the dip stick and verify it at least has the correct oil level.

[BigWhite]

I doubt it's related, if anything it would be the other way around since 5w is thicker than 0w in cold temperatures.


Sent from AutoGuide.com Free App

[beer4799]

oxygenated fuel.....

[beer4799]

oxygenated fuel, perhaps...

[xGS]

By any chance, had you increased the air pressure in your tires and then Jiffy Lube returned them to the "factory" setting?

[dr bob]

The 0W or 5W refers to the cold pour/flow viscosity.

From observation only, it appears that the Jiffy-Lube type places buy bulk oil. The installer selects the oil at the dispenser hose. It wouldn't be too far-fetched to think that a thicker oil was accidentally used.

The Pilot is the first car I've owned that calls for such low-viscosity oil. K's 4Runner uses 5W-30, while my somewhat-vintage Porsche 928 is old-school with 9 quarts of 15W-50 in circulation. When I changed the oil for the first time in the new Pilot, it seemed a LOT thinner than what I'm used to. Since it's not going to see much cruising at 170 MPH autobahn duty, I'm sure the thinner stuff is fine. I did need to tighten the oil filter a bit more than I'm used to, after getting just a tiny dribble/leak on start-up with the thinner oil. I may switch to grease on the gasket next time.

[whizmo]

Guys, to put some technical perspective about how it is flat impossible to get huge changes in fuel mileage with relatively minor changes in oil viscosity, only about 5% of the total power in an engine is internal friction, and most of this friction is not affected by oil viscosity. At best, any change in oil viscosity, even a very large one, is going to lower the efficiency of the engine by a percent or two, not the 15% reductions in fuel efficiency reported here. And if the engine were having to work 15% harder to overcome internal friction, there is no way you could dissipate this much energy from the internal engine parts - the engine would melt.

Final nail in the oil viscosity change theory is that the OP reported that fuel economy went down with thinner oil, exactly the opposite of what you would expect.

Likewise, E10 fuels result in about a 3% decrease in fuel economy over pure gas.

Tire pressure might be a significant contributor but not the whole reason. If you went from dramatically over-inflated (say 40 psi) to somewhat under-inflated (say 28 psi), you might lose a couple mpg. Certainly checking tire pressures would be something to immediately do as a general effort to eliminate variables.

As I said, we're barking up the wrong tree. Something else changed. I don't know whether it is a mechanical issue with the car, change in driving patterns, bad/insufficient data, whatever, but it's not the oil or fuel.

- Mark