Poor mileage on 98 Toyota RAV4

[Nunavut Boy]

I bought a used 98 Toyota RAV4 and I only got 218km off the first tank (cap. approx. 58L (15gal)). What up with that?
Relevant info:

Car has 120,000km
Was checked by mechanic and deemed ok prior to purchase
Most trips are short and engine probably does not reach proper operating temp
This is in a subzero environment (increased rolling resistance due to cold?)
Car is manual transmission and AWD
Power steering pump/belt squeals on startup and lasts ~20 sec. Belt appears to be tensioned well. (I will change belt and fluid to ATF fluid when it gets warmer)
Car is plugged in every night
I avoid excessive idling (I idle it probably 2 mins max before driving)

Is this normal?

(I should add that a parts 2002 RAV4 came with this car (was totaled from side, still drives) and if some longshot part might be defective and is easily replaced, I can do that)

Edited to add:

Car starts and idles normally
Exhaust does not smell rich

[Rick]

Here is your answer.

Originally Posted by Nunavut Boy

Most trips are short and engine probably does not reach proper operating temp
This is in a subzero environment (increased rolling resistance due to cold?)
and AWD

Stop and go kills fuel mileage
Cold start and warm up kills mileage
AWD puts a dent in mileage

[Nunavut Boy]

REally? I understand that those things would hurt gas mileage, but ~9mpg with a 2.0L engine? Huh.

[Mr. Slant]

Odd.
How short are your trips?
Are they all stop and go?
I have a Ford Taurus that gets 11.5 MPG if I start it up on a cold day and drive the 1.2 miles to my neighborhood barber. There are probably 7 stop signs and I can't get above 30 MPH at any point.

[Mr. Slant]

Oh, and at low speeds and holding driving style constant, 90% of your gas mileage differences come from weight. Your engine size is almost completely irrelevant for MPG purposes.

[Leaffan]

I have a 4WD Grand Cherokee and I probably get about 15 miles to the gallon on cold short trips. That's on a 4L, 6 cylinder engine.

I have a fuel/mileage computer that I check often, so that's pretty accurate, but then again I live in the country with few stop signs and no traffic lights. I never idle before driving either.

[Rick]

Originally Posted by Mr. Slant

Odd.
How short are your trips?
Are they all stop and go?
I have a Ford Taurus that gets 11.5 MPG if I start it up on a cold day and drive the 1.2 miles to my neighborhood barber. There are probably 7 stop signs and I can't get above 30 MPH at any point.

A cold day for you and a cold day for the OP have two slightly different meanings. Checking the weather for his town yesterday the high was -12, and it was -20 last night.
Cold start enrichment is huge. It can easily double the amount of fuel injected.

[Mr. Slant]

Oh, very valid point.
My mid-sized sedan probably gets better overall mileage than the OP's SUV.
My unstated suspicion is that in an adequately short commute, 9 MPG is neither objectively good nor objectively bad in the OP's situation.

Still sucks in the subjective sense.

[Rick]

There could be an issue with a thermostat opening too soon, or a temp sensor that is reading low, both of which would put a constant enrichment into the car. A plugged air filter could also be a problem.
A competent technician should be able to check these things in just a little while.

[Really Not All That Bright]

I don't think weight is the problem. The curb weight of a '98 RAV4 is ~1200kg. A '98 Taurus' curb weight is 1510kg, according to Wiki.

[pulykamell]

Originally Posted by Rick

A cold day for you and a cold day for the OP have two slightly different meanings. Checking the weather for his town yesterday the high was -12, and it was -20 last night.
Cold start enrichment is huge. It can easily double the amount of fuel injected.

Do summer and winter blend gases make any difference? I notice that even in relatively mild winter temps (32F or so), during the winter I can barely get 300 miles from a full (13 gallon) tank of gas, while in the summer I get 400+ miles, all highway driving. Even now, when it's about 40-50, I'm hitting half tank at about 150 miles. Or is the difference completely attributable to the reasons you've stated? That's a difference of about 30 mpg vs 23 mpg, and this isn't in snowy stop-and-go driving situations. Does that sound reasonable to you? I can get as high as 34/5 mpg in the summer on the highway, although 30/1 is more average.

[Really Not All That Bright]

Originally Posted by pulykamell

Do summer and winter blend gases make any difference? I notice that even in relatively mild winter temps (32F or so), during the winter I can barely get 300 miles from a full (13 gallon) tank of gas, while in the summer I get 400+ miles, all highway driving. Even now, when it's about 40-50, I'm hitting half tank at about 150 miles. Or is the difference completely attributable to the reasons you've stated? That's a difference of about 30 mpg vs 23 mpg, and this isn't in snowy stop-and-go driving situations. Does that sound reasonable to you? I can get as high as 34/5 mpg in the summer on the highway, although 30/1 is more average.

I'm told that rear window defrosters use so much power they can noticeably affect fuel economy. Same goes for the A/C.

[enipla]

Just chiming in about MPG.

I have an ’06 Pathfinder. I’m was used to getting about 18 + mpg average. Same drive every day. It’s VERY VERY high altitude, two lane mountain highway roads.

This fall, I replaced the OEM BFGoodrich Rugged Trail tires (truly bad, bad tires) with BFG AT KO All terrains. They’re 8 ply fairly aggressive heavy tires.

Between that and the winter blend gas, my MPG went down to 16+ or -.

Since I’m approaching the end of the warrantee, I had a Nissan dealer check out the car. Do a diagnostics.

They said that it was a combo of the tires and winter blend gas.

[enipla]

Originally Posted by enipla

This fall, I replaced the OEM BFGoodrich Rugged Trail tires (truly bad, bad tires) with BFG AT KO All terrains. They’re 8 ply fairly aggressive heavy tires.

opps. Make that six ply on the tread, and three on the sidewall.

[Mr. Slant]

Originally Posted by Really Not All That Bright

I don't think weight is the problem. The curb weight of a '98 RAV4 is ~1200kg. A '98 Taurus' curb weight is 1510kg, according to Wiki.

That element of my post was in the vein of letting you know that engine size has bollocks to do with fuel economy.

[Mr. Slant]

Originally Posted by pulykamell

Do summer and winter blend gases make any difference? I notice that even in relatively mild winter temps (32F or so), during the winter I can barely get 300 miles from a full (13 gallon) tank of gas, while in the summer I get 400+ miles, all highway driving. SNIP

The number I've seen on forums where folks track this stuff is 10% worse mileage with winterized fuels, even before it gets bitterly cold.

[Rick]

Originally Posted by pulykamell

Do summer and winter blend gases make any difference? I notice that even in relatively mild winter temps (32F or so), during the winter I can barely get 300 miles from a full (13 gallon) tank of gas, while in the summer I get 400+ miles, all highway driving. Even now, when it's about 40-50, I'm hitting half tank at about 150 miles. Or is the difference completely attributable to the reasons you've stated? That's a difference of about 30 mpg vs 23 mpg, and this isn't in snowy stop-and-go driving situations. Does that sound reasonable to you? I can get as high as 34/5 mpg in the summer on the highway, although 30/1 is more average.

Yes, it can make a difference. As Mr. Slant about 10%, more if your fuel is oxygenated. While 7 mpg seems a bit extreme, it is possible. If it were my car, I would do the same things I suggested to Nunavut Boy. Check the air filter, thermostat, and engine coolant temp sensor. If the Air filter is plugged, the car will run rich. If the thermostat opens too early, the car will never get out of warm up mode, and will burn extra gas. If the coolant temp sensor reads low the same thing will happen.

[pulykamell]

Originally Posted by Rick

Yes, it can make a difference. As Mr. Slant about 10%, more if your fuel is oxygenated. While 7 mpg seems a bit extreme, it is possible. If it were my car, I would do the same things I suggested to Nunavut Boy. Check the air filter, thermostat, and engine coolant temp sensor. If the Air filter is plugged, the car will run rich. If the thermostat opens too early, the car will never get out of warm up mode, and will burn extra gas. If the coolant temp sensor reads low the same thing will happen.

I just changed the air filter, but I'll check out the other stuff. I seem to recall being worried last year in February for the same reason, but my mileage shot back up to normal levels in May or so. We'll see what happens this year.

[Nunavut Boy]

If the thermostat is failing, wouldn't that mean the heater would not be throwing off heat? My car's heater works quite well.

Does the coolant temp sensor run the temp gauge in the instrument cluster? Mine does work if I drive it long enough.

The airfilter was checked by the mechanic before I bought it and he said it looked OK.

Shop rates are horrendous up here and appointments to get your car looked at are hard to come by. I'd rather not take it in if I can help it.

[Mr. Moto]

Another thing I'd do is switch immediately to synthetic oil. You have a midlife engine, low temps, and stop-and-go driving, and synthetic oil will help in all of these situations - particularly the first two.

[Mr. Slant]

Originally Posted by Mr. Moto

Another thing I'd do is switch immediately to synthetic oil. You have a midlife engine, low temps, and stop-and-go driving, and synthetic oil will help in all of these situations - particularly the first two.

Cite on synthetic being helpful for:
midlife engine
stop-and-go driving,
excluding sites from oil blenders or marketers?

Point conceded for low temps, so long as low temps are defined as under -20F.

On edit:
Oh yeah, if you're not doing it already, I suggest running 0W30 in this vehicle during the non-summer seasons.

[Mr. Moto]

A cite shouldn't be necessary - synthetic should help prevent gunk buildup in the engine, and on an engine with 120k miles, this is important. And yes, it will impact mileage.

Punishing this engine as much as the low temps are the short runs - consider the environment here. This engine starts cold and seldom fully heats up. If you think synthetic would be helpful just for the temps, this is compounded by these other conditions.

[Rick]

Can I play?
Synthetic? IMHO a great idea. Toyotas have been known to sludge, and synthetic will help keep that in check. BTW sludging is worse in cold climates. So from where I sit in sunny California synthetic looks like a good idea.
What weight to run at what temp. The answer to this is simple. Your owner's manual has the correct information. Period. No one you meet on a message board will know more about the engine in your car than the engineers that work for Toyota, designed it, and put the oil specifications in the owner's manual. I include myself in that group of people that you come across on a message board.

Nunavut Boy If you T-stat is bad, the heater will blow cold air, if it is only partway bad, the air will still be warm. Let's say your thermostat is supposed to keep the coolant at 195F. It goes partway bad and the coolant only gets to 145F. You will still have warm air from the heater, although you might have to move the lever a little further into the red to get it. But the computer will see that your engine is not hot, and will add extra fuel. MPG goes into the shiter.

[Really Not All That Bright]

Originally Posted by Rick

Nunavut Boy If you T-stat is bad, the heater will blow cold air, if it is only partway bad, the air will still be warm. Let's say your thermostat is supposed to keep the coolant at 195F. It goes partway bad and the coolant only gets to 145F. You will still have warm air from the heater, although you might have to move the lever a little further into the red to get it. But the computer will see that your engine is not hot, and will add extra fuel. MPG goes into the shiter.

That actually totally explains a problem I've been having since I had a blown radiator replaced. The engine won't reach the normal running temperature, and the heating won't blow anything but cold air on cold days.

[Nunavut Boy]

Thanks for the reponses everyone. I think the cold has more to do with it than anything. The weather here has been a lot warmer than it has been and I've managed to get 80km out of a quarter tank so for. I'll keep watching it as it warms up, but I suspect it's the damned cold.

I will also change to synthetic oil when i fix the power steering in a couple of months.

[Rick]

Originally Posted by Really Not All That Bright

That actually totally explains a problem I've been having since I had a blown radiator replaced. The engine won't reach the normal running temperature, and the heating won't blow anything but cold air on cold days.

Change the thermostat, it should not be that hard, or that expensive. You should see a pick up in mileage right away. At 9MPG, it won't take long to recover the cost of the t-stat.

[Mr. Slant]

Originally Posted by Mr. Moto

A cite shouldn't be necessary - synthetic should help prevent gunk buildup in the engine, and on an engine with 120k miles, this is important. And yes, it will impact mileage.
SNIP

I've read gobs of data on this and never seen any solid evidence to support the two claims I demanded cites for... hence the request.

[Mr. Slant]

Originally Posted by Rick

Can I play?
Synthetic? IMHO a great idea. Toyotas have been known to sludge, and synthetic will help keep that in check. BTW sludging is worse in cold climates. So from where I sit in sunny California synthetic looks like a good idea.
What weight to run at what temp. The answer to this is simple. Your owner's manual has the correct information. Period. No one you meet on a message board will know more about the engine in your car than the engineers that work for Toyota, designed it, and put the oil specifications in the owner's manual. I include myself in that group of people that you come across on a message board.
SNIP

The lower end of 5W30 working properly is at -25F.
You're right, though, you should listen to your manual on these things, *especially* with regards to the number to the right of the W. I would never advocate messing around with that.

[Madd Maxx]

If the vehicle sat for a while before you bought it, the fuel filter may be partially clogged with gunk from the gas tank. Changing the fuel filter shouldn't be that difficult or expensive and should help the gas mileage improve.

[pulykamell]

Originally Posted by pulykamell

I just changed the air filter, but I'll check out the other stuff. I seem to recall being worried last year in February for the same reason, but my mileage shot back up to normal levels in May or so. We'll see what happens this year.

Well, I just wanted to come back and report what happened. It seems that with my Mazda 3, during the winter months, even when there's no snow or if it's not particularly that cold out (just above freezing), I get somewhere in the range of 25-27 mpg highway. I just got back from a trip to Quincy, and I averaged just over 32 mpg down, and am on course for about 34 mpg back.

At any rate, it seems that for me, a 7-9 mpg swing between winter and summer mileage is normal. (This is all based on highway mileage).