Fuel economy 'how-to' thread

[opelbits]

Skinny tires and roll up the windows. No passengers helps, too.

[tracyfam]

I noticed something interesting is some of my past MPG tracking charts. I got better gas mileage in the August through October and worst seems to be in February through April. This is on two different vehicles and (74 Opel Wagon, 92 Geo Metro) over the course of three years of tracking. Milwaukee WI area gas. Anyone else notice different mileage at different time of the year?

[Paul]

When the weather is colder most people let their warm up for several minutes before driving. This will usually knock down milage a bit. Also in cooler weather, the car will be driven a distance before the engine get up to full temperature which reduces fuel milage...

[jordan]

In the summer the fuel economy of my saab averages to around 29-31 mpg and in the winter it is about 24-25mpg all the time (newer saabs along with other cars have a digital readout of certain things such as average speed, fuel economy, distance before empty tank) I always think that my fuel economy will creep up, but now it doesn't look it. Cold weather definitely changes fuel economy.

[ungermm]

Originally Posted by tracyfam I noticed something interesting is some of my past MPG tracking charts. I got better gas mileage in the August through October and worst seems to be in February through April. This is on two different vehicles and (74 Opel Wagon, 92 Geo Metro) over the course of three years of tracking. Milwaukee WI area gas. Anyone else notice different mileage at different time of the year?

There are states that sell oxygenated gas during the winter months that very well could lead to the lower mpg you have experienced. Check out this article and check your state to see if it's one of the states forcing the sale of it.

Blame California Legislature for poor gas mileage

[ungermm]

I did a little more searching on oxygenated gas and came up with this from Dr. Bill Watenburg's site. [PushBack] What’s Wrong with California’s Reformulated Gas

[namba209]

If you read the link in the previous post and think it's a bunch of garbage, you're wrong. Here's what happened to me in my old El Dorado motorhome, two stories and they acually did happen. First, I was coming back from a model boat race, and going up a steep hill the fuel in my main tank moved below the pickup and I ran out of gas, so I switched over to the full reserve tank and immediately got the engine to start again and up the hill I went, at a much higher speed than I was with the newer oxygenated gas. So, just for grins and giggles, when I was on a flat road I switched between the two tanks holding the gas pedal at the same position. The difference was amazing, I got 7-10 MPH more on the old "summer" gas than I did on the newer "winter" gas. Second story. One the way back from a dog show, I ran out of gas, looking for a gas station, so I switched over to the reserve tank and almost immediately, the pressure surge from the reserve fuel tank electric pump blew my fuel line apart, in the engine compartment. Needless to say a fire ensued. I got the fire out within seconds and got the dogs out of the rig. Margaret just happened to be driving her T-Bird along on that trip and took the dogs home. Afterward, she said she would not step foot in it again. She almost cried when I showed up in it the next day. That was the last time the rig was used.

[West Coast GT]

If I remember my physics correctly we run reciprocating engines with a 1 to 15 ratio (by weight) gasoline to air. That puts us near the upper explosive range. Sure, we could economize and lean the mixture for better economy, but I think we would run hot and burn holes in the pistons.

And isn't that basically what all of these economizer gadgets do; lean the mixture?

On another note:
I've been hearing about water-spray injections for 40 years now. You fly-boys; didn't the Air Force experiment with these systems in their piston and turbine engines?

And I believe the Motor-Home crowd has been known to use water-spray for long steep hills. (But do they spray into the carburetor, or are they spraying the radiator?)

[baz]

water spray into the carb or even better a water methanol mix
has been used for many years , the first time i heard of its use was in german WW2 fighter planes to boost power on take off and in dog fights (when you see a photo of a FW 190 they almost always have a tank under the center line this is for a meth /water mix)

it is sprayed into a jet engine on a non after-burner engine to do the same thing right up to and including the B52

[namba209]

ADI or Anti-Detonant Injection was used extensivley on WW II aircraft, primarily the heavy bomber and cargo aircraft. It was a mixture of water and alcohol. The primary purpose was to allow the flight engineer to lean the engine out and inject the ADI to prevent holing the pistons. The ADI fluid in reality would make the mixture a lot more dense, resulting in much more power at the same RPM. IIRC the B-47 was the first production aircraft to use ADI on a jet engine powered aircraft, this was followed by the KC-135, the B-52, and the F-105. The F-105 was the only fighter aircraft to use ADI and was also the only aircraft that used ADI in conjunction with an afterburner. ADI was discontinued on the KC-135 and B52 when they were modified to use Turbo-Fan engines. They generated much more thrust than the axial flow turbine engines with ADI, at a lower power steeing. HTH.

[bullmoose]

Anyone ever test to see what happened to their gas mileage with different oil viscosities? I was running 5W-30 in my GT for a while, and when I replaced it with 20W-50, there was an immediate and noticeable drag on the engine. I had to adjust the idle on the old solex to compensate. I'm curious if anyone else ever noticed this and decided to see what happened to their gas mileage? Since the service manual says 10W30 is the recommended oil, what's the harm in low viscosity vs. higher. Either way, my ol' girl leaks like a sieve. I'd do it myself, but at this time, the ol' girl has too many other issues to work through before it becomes a reliable test bed.

[bullmoose]

Has anyone tracked to see how replacing the stock fan with an electric one affected their mileage? What'd it do for you?

[Paul]

Oil viscosity WILL impact fuel milage!!! Why do you think all of the car mfgs went ot 5W-30 and 10W-30 motor oil! I thought the original specification for Opels was 10W-40, BTW.... Synthetic oils offer more improvement in fuel milage.

The August issue of Circle Track even does a Dyno comparison to illustrate the increased HP from synthetics and lower viscosity... Interestingly enough, some of the HP increase comes from a reduction in HP consumed by the oil pump........

[kwilford]

In fact, all newer Honda's call for 5W-20 oil. I was only able to get that for my 2003 Odyssey in a Mobil 1 synthetic a couple of months ago. Only Honda was selling it for while. Apparently the new Honda engines have such close tolerances that they require the lower viscosity oil as way to improve mileage, even beyond the typical 5W-30.

[hrcollinsjr]

Originally Posted by kwilford In fact, all newer Honda's call for 5W-20 oil. I was only able to get that for my 2003 Odyssey in a Mobil 1 synthetic a couple of months ago. Only Honda was selling it for while. Apparently the new Honda engines have such close tolerances that they require the lower viscosity oil as way to improve mileage, even beyond the typical 5W-30.

Keith,

Why not go all the way? Mobil offers 0w20, 0w30,0w40. I wrote a letter to Castrol years ago inquiring about different viscosities possibly voiding the warranty on my then new Dodge Caravan. Their response was that as long as it met the API/SAE standards it wouldn't void the warranty.

Harold

[kwilford]

Originally Posted by hrcollinsjr Keith, Why not go all the way? Mobil offers 0w20, 0w30,0w40. I wrote a letter to Castrol years ago inquiring about different viscosities possibly voiding the warranty on my then new Dodge Caravan. Their response was that as long as it met the API/SAE standards it wouldn't void the warranty. Harold

The "0W" refers to the low temperature viscosity, which would help low temperature cranking drag, but not "running" drag, so a 0W20 provides the same running drag as the 5W20. Some "experts" suggest that the wider viscosity ranges created by viscosity enhancers can be helpful during wide ranges of operating temperatures, but create a lower-durability oil, prone to more rapid breakdown. There's no free lunch

[bullmoose]

...but has anyone actually compared their gas mileage while running different viscosities of oil? What was the difference? I'm curious to know what kind of fuel efficiency I could expect running 20W-50 vs 5W-30 or something along those lines. Any real-world gas mileage numbers out there?

[hrcollinsjr]

Originally Posted by kwilford The "0W" refers to the low temperature viscosity, which would help low temperature cranking drag, but not "running" drag, so a 0W20 provides the same running drag as the 5W20. Some "experts" suggest that the wider viscosity ranges created by viscosity enhancers can be helpful during wide ranges of operating temperatures, but create a lower-durability oil, prone to more rapid breakdown. There's no free lunch

Everything I've ever read said that the oil doesn't wear out just picks up impurities and the additives are lost. The wider range viscosity oils aren't usually recommended for heavy duty severe service type equipment if they are operated in moderate temperatures.

0w20 or 5w20 they are still as thin as water. Amazing that it can lubricate an engine well enough to keep it from seizing!

Harold

[hrcollinsjr]

Originally Posted by bullmoose ...but has anyone actually compared their gas mileage while running different viscosities of oil? What was the difference? I'm curious to know what kind of fuel efficiency I could expect running 20W-50 vs 5W-30 or something along those lines. Any real-world gas mileage numbers out there?

I don't know about actual mpg difference but when you can tell the engine is slower to rev after changing from 10w40 to 20w50 it has to be measurable. Probably has a greater effect on lower hp engines like our Opel's.

Harold

[opelwasp]

Well I am going to divert from this fascinating discussion about oil. I rebuilt my engine which helped and installed a new cam. 252 advertised duration and .420 lift intake and exhaust. A "street" ported intake manifold to match the 38 dges, and a Pacesetter header. As long as I kept my foot off the floor it got great gas mileage, a consistent 34 MPG. After 3500 RPM in 4th gear I could practically watch the gas gauge drop though.

OK, OK I ran Royal Purple oil too, 10w40. Must have been the oil.

[bullmoose]

You sure it wasn't the .042 lift? At least you don't have to worry about the lobes wearing down too much.. I'd say they'd probably only wear about .042 over their life Once it does, feel free to beat me with that "bump" stick. I don't know why, but but that made me LMAO.

[wrench459]

Originally Posted by opelwasp As long as I kept my foot off the floor it got great gas mileage, a consistent 34 MPG. After 3500 RPM in 4th gear I could practically watch the gas gauge drop though.

Now what's the fun in keeping the gas pedal off of WOT!!
The "beep" with MPG lets have fun with our cars
Yours truly

[opelwasp]

Originally Posted by bullmoose You sure it wasn't the .042 lift? At least you don't have to worry about the lobes wearing down too much.. I'd say they'd probably only wear about .042 over their life Once it does, feel free to beat me with that "bump" stick. I don't know why, but but that made me LMAO.

Ya got me. I put the wrong number in. It was .420 lift. Doh

[CoriolisSTORM]

My Caliber has 5W-20 Mobil 1 synthetic in it now. An electric fan on a Wrangler will free up 5-10 HP for the motor, and I assume a dry sump system would be of further help, I can not vouch for what it would do to an Opel motor. Maybe a better intake as well... Oh yah, nobody has discussed it, but get some Low Rolling Resistance tires like you see on the hybrids too. They'll help you out, but they'll probably ride bad and are noisy and are hard to find in decent sizes.

[bullmoose]

Well, since I started it, I now feel obligated to check it out.. So.. Hopefully by the end of the weekend I'll have everything running to the point that I can top off the tank and run a couple hundred miles with the 20w-50 and see what happens, then I'll go back to 5w-30 and see. All my driving will be in town.

In my effort to get better mileage, I've within the last couple months replaced the solex with a 32/36 weber, added a pertronix, 105 Amp alternator, electric fan, and this weekend it'll have an electric fuel pump. I haven't driven it enough to see what the mileage was before all this, but it wasn't any better than 15mpg. The exhaust is crap, with no pipe behind the cherry bomb. That's the last thing I need to do before I think I've done all I can for the moment.