I dunno...have you done anything to your truck as of late...?...new tires, tune up, oil change, or that kind of thing. The weirdest things seem to adversely affect the gas mileage in these trucks.

I've had the same kinda thing happen to me lately. The last couple years, driving my normal daily commute, I have been used to filling my truck between 360-380 miles; and have averaged around 19.5 MPG. The last 6-8 months, my low fuel light has been going on between 320-340 miles and am averaging right around 18.

Not sure why I am losing mileage the way I am. Of course, I have done several things to my truck in the last 6-8 months that may be dragging my mileage down a bit (new tires (they might not have low rolling resistence like the LTX M/S) and put a Leer topper on (150 lbs of added weight).

On the other hand, I have done a few things that should be helping the mileage (new plugs, complete service including VTM/tranny fluid and gear/oil and filter change).

I have had this truck for almost 8 years now and, historically, the mileage is around 17 overall in the winter, but kicks up another 1-2 MPG after it warms up, and we are no long running on winter gas. This year it went from around 17 in the winter to around 18 this summer. The best I have gotten is on a long trip and I got around 21 MPG...when previous years I was getting closer to 23 on highway trips/drives.

Long story short, I don't know what may be causing your mileage decline, as I cannot figure out mine. Maybe it's time to do the engine/tranny re-learn procedure and start over...I dunno.

 

Mine has dropped an average, according to my fuelly, about 1 mpg.

Here is my theory:

Ethanol!!!!!!!!!!!!!!!!!!!!!

At the same time this is going on with the truck, my small engine equipment here on the farm are running crapping and becoming hard to start. We are having the same problems at work with the grounds keeping equipment as well as our white fleet that runs on gas.

Either the ethanol is breaking down really bad, or more is in the gas then we are told. Gasoline's smell has changed.

 

Here is my theory:

Ethanol!!!!!!!!!!!!!!!!!!!!!

Could be! Not only do I drive the same way and the same route on a consistent basis, but I also fill up at the same pump at the same station - time after time - in a robotic manner. My fuel economy usually hangs a little over 17 MPG, but there have been several times where it increased to 19 MPG for several weeks at a time before going back to "normal". I'm in one of the increased periods at the moment and have been averaging about 2 MPG better for weeks now. I can't seem to associate it with weather or any other factor. I'm surprised I'm getting 19 MPG considering my A/C is running "wide open". Fuel economy was lower during mild weather. *shrug*

 

Validate that the parking brake is fully released - found an Accord that the mileage was dropped a few MPG and the parking brake was dragging the car.

 

My 2013 RTL stated out with great MPG, been dropping off ever sense. After about 3K miles average is now down to 18.7. 300 mile road trip Monday with 200 of it on interstate was 19.1.

 

One more thing: I've NEVER bought into or experienced the "MPG improves after break-in" fantasy. EVERY vehicle I've ever purchased (quite a few) starts out at or near the EPA ratings for the first few tanks before settling down into its lifetime average. I attribute this to very gentle driving when something is new for a few weeks until the "new" wears off and I get more comfortable with it.

 

How many miles does it have on the Odometer?

 

Probably about 4000-6000 miles more now than when the OP originally posted.

 

Winter blend...enough said.

 

Is winter blend normally out as early as August?

 

Has anybody ever listened to Kevin Rutherford on SiriusXM's Road Dog Trucking channel? Yes it involves big rigs not Ridgelines, but they get into some interesting discussions on fuel economy and what can effect it, and so on. Kevin sounds very knowlegeable. It's on right now.

 

Well, got my worst mileage ever this weekend. The truck was fairly loaded...enough gear for a weekend for 4 people...and I was pulling a trailer with a ATV on it...for about 275 miles, mostly interstate...and got 12.49 MPH on the trip back. Granted, it was cold, and we are running winter gas here in WI...but that still sucks.

I realize I will get lower MPG's when towing anything, even a small trailer, but I figured I would get around 15 MPG, not 12.49. And this is after an oil change, and not too long after new plugs, the water pump/timing belt service, etc.

Thank God I was able to get gas for just over $3 a gallon at a couple places...other wise it would have been one expensive weekend...!

 

Is your trailer enclosed? If not, does it have tall sides?

 

I wonder if you would benefit from changing out your O2 sensors?

 

That thought had crossed my mind. As I mentioned above...My mileage has taken a hit after I did the timing belt service, which included changing the plugs. Not sure what the dealio is, as I thought the MPG's would go the other way after the service, and it sure is annoying.

I knew I was not going to get the best mileage, since the RL is a truck after all, but I have been averaging 20+ on long trips and around 18.5 on my normal daily commute. Now I am lucky to get 18 on the highway and 16 on my daily commute.

 

My mileage varies like the OP. I started out at 19mpg then spent a few months at 17mpg and now I am sitting solid at 16mpg. Go Figure....

 

Two explanations that do not involve a mechanical change:

1. You are now used to your truck and you aren't babying it anymore. It takes very little spirited driving to change results for a tankful of fuel.

2. Your social life improved and you are making more trips that aren't routine, so there could be more cold starts, short trips and non-highway driving.

Both have happened to me at times. But, if I take it on the highway under comparable conditions to a previous reference test, let it get warmed up, reset the trip computer and let it cruise, I get the same results. It's roughly 24 MPG at 62 MPH (100 km/h).

 

Last week I put new Michelin Latitude tour tires on my 2010 ridgeline. Before the tire change 19 -20 mpg consistently. After the tire change 17-18, for the last week. And the change in mileage happened immediately after I left Sears. I reset the mpg monitor to see what would happen. Even on hwy 1-2 mpg less than with the oem tires, which were beat to heck. I just purchased the truck ( my second Ridgeline), and am considering asking Sears to put some LTX on this thing. Any thoughts???

 

Get the LTX if you can. There are some informative posts from our old Honda insider Kodiak on the matter here, here, and here.

 

Roughly 2.5 to 3 MPG. The biggest improvement was in town driving.

 

Really, that much? That is a significant improvement. What did you end up spending on all the sensors? Around 300?

 

IIRC, it was around $330 from RockAuto.com for NTK/NGK and I did it myself. The mileage/performance benefit seems to depend on how bad or lazy the old sensors have become before replacement.

The most extreme mileage/performance improvement case I've seen was on my 95 F-150 300 CID six with over 220,000 miles. That is a OBDI vehicle that only uses one O2 sensor on the exhaust manifold. Those sensors should be changed at 60,000 miles. While it was not throwing a CEL code, changing the sensor remedied the bucking that was occurring when attempting to go up a hill in 5th gear and improving highway mileage from 15 to 18.5.

You know, I don't spend money buying fuel and oil additives, special air filters, or attachments that are guaranteed to improve performance. But I have found that keeping the emission system (e.g. fuel and fire regulation) components squeaky clean and working at their best, results in old cars with over 100,000 miles that run like new.

 

Put some HEET in it........I hear it solves all sorts of problems...........after all alcohol is great for MPG.....:act035::act035::act035:

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