Here's a few myths that I have been told about cars. A couple I have since found out answers too but I'm not sure about the others and would appreciate any voices of experience/knowledge:

1. Don't let gas guage go below 1/4 because you'll suck up the rust and gunk in the bottom of the gas tank.

2. If you leave the defroster on you can crack your windshield.

3. Not running the A/C will save you money. Only true below 45 mph or so and if you don't run it once a month you can actually cause the freon seals to go bad resulting in lots of money wasted in repairs.

4. You can fry your alternator by jumping off other people. I think this would require many, many jumps to do...

5. Adding cold water to hot engine can crack the block. My policy is if I absolutely have to add water I wait until I can get the radiator cap off without burning myself and then I add water while the engine is running. Personally I think it's best to wait until cool but if you gotta get where you're going and can't wait...

6. Leaving 4runner rear window down can drag in exhaust fumes and kill you. I think this could be true so I make sure that if it's down, that I have both front windows down, maybe sunroof, too, and that I'm driving fast enough to keep airflow from front to rear.

 

send them to mythbusters lol. As for the 4runner window. get your exhaust bent to come out on the side.

 

I've heard about #4 before. I generally leave my car off when I jump other people, but I'm not sure it's a big deal.

45 mph is supposedly the cutoff limit for AC efficiency. Below 45, crack a window. Above 45, the drag of having a window open sucks more power than having the compressor on.

 

#2 with the defroster happened to me in a 89 2-dr Honda Accord, blew so hot that it would feel like it was burning your hands/feet.. left in on for 10 min on highway, with below 0 windchill.... cracked all the way across on the bottom

 

#1 I have only head not to let it go to empty because of that. Never heard of below 1/4.

 

1. I run down to below the E all the time and i've never had a problem. You do realize it sucks gas in from the bottom anyways, NOT the top.

2. The defroster cant crack your windshield, it's just air. Does the sun or ice crack your windshield? I could see extreme changes in temp, MIGHT do it (like -40 to +40) but no.

3. True, the A/C puts a load on the engine and uses more gas. Completely true (no matter what speed).

4. No. You can blow your ECU fuse if you hook up the cables backwards tho. Only imports have a fuse on the ECU, domestics, you have to replace the whole computer! (if it blows)

5. I agree with you, but no, it wont crack your block, you're pouring it into the rad where it will instantly heat up. ALTHOUGH, if all you have is water in your rad and the temp is below freezing, it CAN crack the block when the water expands and turns into ice inside the block.

6. I dunno about kill you, i do it all the time But it only does it when the front windows are open, because of vaccum and physics and ˟˟˟˟˟, what i do is open the front windows all the way, the open the rear one until i kinda smell gas, then put it up a bit. Or just run all the windows open and deal with it, it's not going to kill you, would standing beside a highway kill you?

 

#3 is proven true.. you need to watch myth busters!!!!!!! above 45 you waste more gas.. below 45 you save gas with the ac off

 

#3 is definately true. in a subaru you can actually feel the engine pull with more power as you turn off the AC and drag is let off of the engine

 

#3, as for the drag of having the windows open, with our rear windows, doest that cut MOST of the drag, since it just flows thru, instead of getting trapped back there?

as for the gas tank, i never let it get below 1/4 so that, in an emergency, id have enough gas to get well away from here, or back home if im at school.

 

try going at a steady speed up a steep hill and then turning on your AC full blast, I promise your car will slow down and you will have to step on the gas pedal harder to maintain the constant speed you had before.

 

its dependant on enegine size, a larger v6 and v8 wont really expierance this vs a small 2.0L I4 or small 6.

 

I can do over 120 miles on a 1/4 tank.

 

I found I could lower my rear window a certain amount before it would pull in exhaust fumes. All the way down and it will, but a little will pull air out as there is a partial vacuum created behind the vehicle as you drive. Usually have the sunroof open or the front windows down a little to create a nice front->rear air flow.

 

#1....your fuel pump is at the bottom....it ALWAYS sucks gas from the bottom of the tank...

 

The light really lies, in my old camry I had 18.5 gallons-when it said it was empty I had 3 gallons left maybe. The T100 has a 24 gallon tank, light comes on at 19-20 gallons used up. I get about 17mpg, that means I have another 4-5 gallons left..thats over 50 miles! This is way past the E and the light on too!

 

1. Let it go as low as you want, it is fine.

2. Not if you leave it on, but I supposed if the temperature difference is enough and sudden it could happen.

3. Yes it will, however, I have heard that the gas mileage you lose by having all your windows open and driving instead will be approximately equivalent to windows closed but AC on.

4. I have never heard this and I jump people frequently with my truck on.

5. Add the water to the overflow instead.

6. Not enough to kill you, if you have the rear window open I assume you have others open. You may notice it, but it won't kill you.

 

No wonder my kids slept so well on my trip out west this summer. I had the back window down at night and opened the sunroof. Nice cool air coming through, but I think it gets sucked in the back and exits through the sunroof.

I'm no physicist though.

 

1 - if you always run it to almost empty youll remove the rust and gunk all the time, therefore no build up. and thats what a fuel filter is for. i remember this one from the 70's
2 - could happen. i dont live in the snow or even very cold but i keep my selector to defroster all the time (fan off) so the air doesnt blow on me.
3 - busted at 45mph on mythbusters.
4 - ^ obviously if they connected backwards. ive never fried an alternator and my ex used to leave the interior lights on all time
5 - adding cold water to an empty radiator can crack the block or something else, water turns to steam very quickly above 212*F(100*C). but like you said how did they safely get the cap off when its overheating?
6 - i have a deflector on the back that seems to prevent any fumes from entering while driving. w/ the sunroof open i can feel the air being pulled out the back

 

With the gas tank the filter doesn't sit on the very bottom and if you truly ran out of gas and then removed the tank you'd still extract over a gallon of unuseable fuel.