Gas mileage taking a hit

I don't know that being late on maintenance would cost 4mpg, however, you might check to see if the gas stations in your area have switched to a winter fuel formula. That can have an effect.

MPG will drop in winter time due to increase rolling resistance from thicker axle lube, wheel bearing grease, tires are a bit stiffer, air is densor so there is more drag and engine uses more fuel during warm up cycle and it never gets as warm and loose in cold weather as it does in hot weather because though coolant temp may be simular, the oil in it is cooler in cold weather and this all adds up to reduced MPG. a 10 to 15 % loss can be expected and he is in that range.

----------------- TheSnoMan.com

of which all shouyld come up to temp within a few short miles.

Meaning more power therefore you dont put your foot down as much useing less fuel.

Every winter I use LESS fuel with cooler air and temps.

Id be looking at air filter or fuel type. Try another gas station and see if it comes up. Or failing that stick a bottle of injector cleaner through your gas tank.

Nope it never does, When I leved where it could get 50 below you where lucky to get 8 or 9 on a trip when you normaly got 14 to 16 even with engine fully warmed up because the tracies, tcases and rear xale never really warms up if it is cold enough even with SYN gear oil, been there, done that.

Yes and nop because it also take more fuel to maintain air/fuel ratio so WOT power will be up a bit but no free MPG here.

. If this is the case it is because your vehcile is to ricjh in warm weather not because it uses less fuel that way normally. MPG will decrease if engine is operating properly in warm weather. THe amout of decrease will depend on tempature and vehicle. FWD cars are effected the least and RWD cars and trucks the most.

----------------- TheSnoMan.com

Now explain the Day/Night secario. I get better milage driving at night rather than during the day. Air temp approx 30Deg C during day and 10-14C at night.

This one is easy, you re using 87 octane fuel which causes ECM to retard ignition timing on a warm day to limit knock BEFORE you hear it (this is the only reason there is a knock sensor of a modern car). At night the air is cooler and more humid which reduces octane requirement of engine (it is not constant) which retards spark less and improves MPG. You cannot retard timing to control knock without loosing efficency but since you never hear it knock you (like most others) assume all is well. ALso if you use A/C, it takes less power at night.

----------------- TheSnoMan.com

Our temps are only now getting around freezing, so its not like we are having bitter cold conditions here.

I may try fuel injector cleaner if my maintenance tomorrow doesn't see any improvement in mileage. Is crazy, I can watch the needle go down.

Usually, I can get to 125kms by the time the needle gets to the second mark on the gas gauge, this tank I barely got 100kms.

I usually fill up at my local station close to my house, perhaps another station may be a good idea to try too.

Thanks for the replies.

Do not worry yourself silly on this because it is quite normal to loose MPG in winter and your loss is about the norm.

----------------- TheSnoMan.com

I keep track of my gas mileage religiously like I said, using a database in my Palm Pilot. I record the current odo reading, litres I pumped, and the price of gas. Past years did not see such a decline, only perhaps 1-2mpg.

Useing AC under 30Degrees C, what ya think Im a sook!?!?!

No AC used day or night during that test.

:o)

Stick a 1gallon plastic tank in the back and run it out of fuel . Then see how far you are actually getting. Your guage may be faulty.

The service guy at Toyota said if there was anything wrong, even a loose gas cap, the check engine light would come on.

If the engine etc is working properly, perhaps there is a hidden drag on the truck like a partically stuck brake?

Turns out the parking brake was stuck on one wheel. I would say that was causing the engine to work harder and burn more gas.

Do "they" change the fuel blend in your area?

Where I live, they change the gas back and forth between Summer Blend and Winter Blend. Everytime they change the blend, my fuel mileage changes.