MPG and short trips

[MysticGold04]

Just a quick question that has been bugging me the last couple of days. I live about 10 minutes - 5 miles from work.

So in the morning, I start the truck, wait about 20-30 seconds and then drive easily to work... rpms are kept about 2000-2500.

On the first trip of the day, my scangauge reads a trip mpg between 13-15mpg.

When I go home for lunch using the same route, mpg tends to be higher at 16-18mpg and usually the trip home after work averages about the same, but I've seen as high as 19mpg on the gauge. Note: same route, same speed and I usually use the cruise control to keep the same speed. Normally 50-55.

I'm wondering if this is because of ambient temps or what? Would switching from a 5w30 to a 0w30 help out in this situation? (not that it needs help, its just odd) Could be the tires warming up with ambient temps...

I'm considering switching during the winter months even though not needed here - lowest is gets here is high teens.

 

[dwendt44]

The ambient temp. has a lot to do with it.
You put your finger on it.
0W oil might help a bit, but likely not enough to really notice.
Temp is reason most people get the best mileage in July/August.

 

[WishIhadatruck]

I have a Scangauge as well and have always noticed pretty much the same thing. The colder the vehicle and its fluids are the worse the gas mileage. Up shifts are delayed, it runs richer, etc. It all adds up to worse gas mileage. I get my best gas mileage on very hot days when I am going home from work during the hottest part of the day. It is very noticable to me even though my trip is 30 miles one way and mostly highway.

0W-30 might help a little but not much.

 

[Winston]

Yes, it is the cold temps. Prius freaks actually use block heaters year round to ensure they get the best mileage even at cold startup.

 

[ChiTDI]

Ambient temperature and also residual heat in the engine would affect mileage for your lunch route and the drive home.

 

[lovcom]

Don't assume that going back home from work will yield the same MPG as going from home to work. Unless your route is perfectly flat, having no inclines nor declines, the MPG will differ.

 

[dwendt44]

The car may 'resist' going to work and be happy to go home at night.

 

[Mamala Bay]

Car sits over night the metal is cold. If you heat the metal takes time to cool off...a heated metal runs better period...I would think it gives better mpg over a cold metal.

 

[oilyriser]

No need at all to let truck warm up, if you're in CA. The first minute, the truck will suck 2x as much gas as in the 2nd minute, so you might as well get it moving with that gas instead of letting it idle. Choose the 5w30 or 0w30 with the lowest 40 degree C viscosity. Blocking the grille 100% will help keep the motor warm, and give you even higher mpg on the way home. But make sure there are openings at the bottom near the bumper in case the rad fan needs to run.

 

[meep]

Using a syn gear lube will make a difference, or at least it has in my cars. Same with T-case if you have it. Less difference in engine - in some cars I've noticed small (
M

 

[Gary Allan]

Try and see if using a lighter oil effects it. I'm sure, as was stated, that synthetics in the rest of the drive train would help.

You never approach 100C with your oil in that cycle. You're pumping (probably) 60 or 70 weight when you turn the key off.

 

[MysticGold04]

Originally Posted By: meep
Using a syn gear lube will make a difference, or at least it has in my cars. Same with T-case if you have it. Less difference in engine - in some cars I've noticed small (
M


Yep, already using Amsoil 75w110 in the diff (it has a locker) Plan is to run T-IV in the trans until next year and then use Amsoil in there too. I think I'm gonna try the new M1 0w30 this winter to see how it does.

 

[Tornado Red]

Originally Posted By: MysticGold04
Just a quick question that has been bugging me the last couple of days. I live about 10 minutes - 5 miles from work.

So in the morning, I start the truck, wait about 20-30 seconds and then drive easily to work... rpms are kept about 2000-2500.

On the first trip of the day, my scangauge reads a trip mpg between 13-15mpg.

When I go home for lunch using the same route, mpg tends to be higher at 16-18mpg and usually the trip home after work averages about the same, but I've seen as high as 19mpg on the gauge. Note: same route, same speed and I usually use the cruise control to keep the same speed. Normally 50-55.

I'm wondering if this is because of ambient temps or what? Would switching from a 5w30 to a 0w30 help out in this situation? (not that it needs help, its just odd) Could be the tires warming up with ambient temps...

I'm considering switching during the winter months even though not needed here - lowest is gets here is high teens.

Many vehicles use more fuel during the warmup period than afterward. So the viscosity of the oil you use is not that important, only the ambient air temp and how long it takes for the engine to warm up.

Also, there is no significant difference between a 0w30 and a 5w30. (There might be a difference between conventional and synthetic oils in these viscosities.)

 

[Gary Allan]

Quote:
Many vehicles use more fuel during the warmup period than afterward. So the viscosity of the oil you use is not that important, only the ambient air temp and how long it takes for the engine to warm up.


Hmm.. I don't agree with this ..at least not quite the way it's stated.

Again, I suggest doing short trip usage with 5w-20 for 3 months. I then suggest doing short trip usage with 20w-50. Compare fuel economy records. Then reaffirm your belief.

 

[Tornado Red]

Originally Posted By: Gary Allan
Quote:
Many vehicles use more fuel during the warmup period than afterward. So the viscosity of the oil you use is not that important, only the ambient air temp and how long it takes for the engine to warm up.


Hmm.. I don't agree with this ..at least not quite the way it's stated.

Again, I suggest doing short trip usage with 5w-20 for 3 months. I then suggest doing short trip usage with 20w-50. Compare fuel economy records. Then reaffirm your belief.

I was not comparing a 5w20 with a 20w50 -- clearly there is or should be a noticeable difference in fuel economy when using these two viscosities.

I was comparing a 5w30 with a 0w30. Again I claim that there should be no noticeable difference.

As for vehicles that use more fuel during the warming-up period... note that I used the modifier "many". I did not claim that this is true for all vehicles... but it is a common phenomenon.

 

[Gary Allan]

Okay, then we're really not dealing with any difference in viscosity that's worth talking about in most sensible terms.

I agree with you.

 

[severach]

Next time you got nothing to do rub the engine until it's 200*F. You'll find it's not as easy as gasoline makes it look. Engine block heaters are only good for transferring the wasted money from your gasoline bill to your electric bill. That's great for your MPG e-pen is but doesn't help the bottom line.

It's cheaper to have bad cold economy than to keep the engine heated constantly.

 

[firemachine69]

I don't know about you Michigan folks, but up here, we use digital outdoor timers...

 

[brianl703]

Originally Posted By: lovcom
Don't assume that going back home from work will yield the same MPG as going from home to work. Unless your route is perfectly flat, having no inclines nor declines, the MPG will differ.


If home and work are at the same height relative to sea level, the MPG will be the same for both trips, assuming no wind.

 

[Quattro Pete]

Originally Posted By: Mamala Bay
Car sits over night the metal is cold. If you heat the metal takes time to cool off...a heated metal runs better period...I would think it gives better mpg over a cold metal.

That would be my guess, too. In the morning, the car is dead cold whereas at noon (lunch) and on the way back from work it's not totally cold due to some residual heat so it takes less time to reheat.