Running low on gas - Page 2 - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

lbroskee · 04-11-2013, 12:08 AM

wtf is 90 octane? i've never seen that

Clembo · 04-11-2013, 08:12 AM

I never let any of my cars get too low, about 1/8 to 1/4 tank is the lowest. With the fuel pumps in the gas tanks of most modern cars, damage can occur and shorten the fuel pump's life.

When the fuel level is low, the pump has to work harder to produce the same pressure because the reduced fuel weight no longer pushes fuel into the pump. Instead the pump must draw the fuel in. There is also less fuel to cool the pump and the overworked pump can overheat.

Most pumps today are pretty rugged and have safety backups but it's not worth taking any chances for me, especially if I'm driving hard.

CaptainSlow · 04-11-2013, 08:17 AM

Quote:

Originally Posted by lbroskee

wtf is 90 octane? i've never seen that

Usually an at-pump mix of regular and premium

I believe manufacturers bias the fuel gauge to make sure people don't run out of gas (make them think they have less fuel than they do)

marcosowns · 04-11-2013, 09:04 AM

The gas light is very fool proof. You should very easily go at least another 30 miles after the light comes on if it is necessary. I've had other cars (Honda/BMW) which I have driven a few miles indicating 0 miles left in my tank. Now whether you should be doing that is a whole different discussion.

Mikem53 · 04-11-2013, 09:15 AM

In tank fuel pumps are cooled and lubricated by the fuel... Best not to run them too low as they can overheat and fail...

Freetime · 04-11-2013, 09:16 AM

Quote:

Originally Posted by Clembo

I never let any of my cars get too low, about 1/8 to 1/4 tank is the lowest. With the fuel pumps in the gas tanks of most modern cars, damage can occur and shorten the fuel pump's life.

When the fuel level is low, the pump has to work harder to produce the same pressure because the reduced fuel weight no longer pushes fuel into the pump. Instead the pump must draw the fuel in. There is also less fuel to cool the pump and the overworked pump can overheat.

Most pumps today are pretty rugged and have safety backups but it's not worth taking any chances for me, especially if I'm driving hard.

I'm pretty sure I read in a warning in the FRS manual that said to NOT run the car low on fuel as it can damage the engine. I usually fill back up around the 1/4-1/8 mark.

lbroskee · 04-11-2013, 09:40 AM

Quote:

Originally Posted by CaptainSlow

Usually an at-pump mix of regular and premium

I believe manufacturers bias the fuel gauge to make sure people don't run out of gas (make them think they have less fuel than they do)

so if i have a station that sells it ethanol free near me, would it b better or worse then regular 93?

strat61caster · 04-11-2013, 12:01 PM

Quote:

Originally Posted by Tucson FR-S

On a related note, I see that the car's computer overestimates average mpg per tank by about 5%. Sound about right?

I've never had it under 6% accuracy, closer to ~8% with a couple off by 10%

I have yet to see an mpg computer that underestimated mileage. Trying to trick you into thinking you're outdoing the EPA figures pisses me off.

civicdrivr · 04-11-2013, 01:49 PM

The lifetime mpg average on the dash shows 28.4mpg on my car. The actual lifetime mpg average is 25.6mpg. Huge difference.

And that damn instant fuel economy reading is a joke.

Sent from my Nexus 4

strat61caster · 04-11-2013, 03:34 PM

Quote:

Originally Posted by civicdrivr

And that damn instant fuel economy reading is a joke.

The only thing it's good for is telling you when you're in "compressor" mode not burning any fuel (or very minimal fuel as the case may be). Otherwise it's basically a throttle position readout.

immortal_suby · 04-11-2013, 04:57 PM

Quote:

Originally Posted by Tucson FR-S

On a related note, I see that the car's computer overestimates average mpg per tank by about 5%. Sound about right?

I have tracked every fillup since new and the computer is consistently 2 to 2.5 mpg over vs. the actual mpg. My calculated average over 7k miles is 29.7 with a high of 32.5

LeeMaster · 04-11-2013, 05:14 PM

I made 340 miles 98% highway trip going on average 85 mph, filled up to 10.3 gallons. Couldve gone an extra 50-75 miles if I wanted to. Touche.

Zero cruise control

civicdrivr · 04-11-2013, 05:32 PM

The most I've gone on a tank was 392.5 miles, that was 12.46 gallons. I have a heavy foot most of the time.

Sent from my Nexus 4

jmaryt · 04-11-2013, 07:00 PM

Quote:

Originally Posted by LeeMaster

I made 340 miles 98% highway trip going on average 85 mph, filled up to 10.3 gallons. Couldve gone an extra 50-75 miles if I wanted to. Touche.

slush,or stick?

04-11-2013, 08:12 AM	#16
Clembo 'Senior' Junior Member Join Date: Mar 2013 Drives: 13 FR-S,08 Mustang Bullitt,06 MX-5 Location: Southeastern CT Posts: 389 Thanks: 117 Thanked 213 Times in 122 Posts Mentioned: 16 Post(s)	I never let any of my cars get too low, about 1/8 to 1/4 tank is the lowest. With the fuel pumps in the gas tanks of most modern cars, damage can occur and shorten the fuel pump's life. When the fuel level is low, the pump has to work harder to produce the same pressure because the reduced fuel weight no longer pushes fuel into the pump. Instead the pump must draw the fuel in. There is also less fuel to cool the pump and the overworked pump can overheat. Most pumps today are pretty rugged and have safety backups but it's not worth taking any chances for me, especially if I'm driving hard. __________________ "You'll never know if you don't try" - Shinroko Momose

04-11-2013, 01:49 PM	#23
civicdrivr Senior Member Join Date: Mar 2012 Drives: 2018 Golf R Location: Richmond, VA Posts: 2,807 Thanks: 5,386 Thanked 1,095 Times in 647 Posts Mentioned: 68 Post(s)	The lifetime mpg average on the dash shows 28.4mpg on my car. The actual lifetime mpg average is 25.6mpg. Huge difference. And that damn instant fuel economy reading is a joke. Sent from my Nexus 4 __________________ Parting out HERE

04-11-2013, 05:14 PM	#26
LeeMaster Red wine Join Date: Oct 2012 Drives: Subaru BRZ(R.I.P) Location: Denied Posts: 1,176 Thanks: 1,268 Thanked 342 Times in 240 Posts Mentioned: 13 Post(s)	I made 340 miles 98% highway trip going on average 85 mph, filled up to 10.3 gallons. Couldve gone an extra 50-75 miles if I wanted to. Touche. Zero cruise control __________________ Last edited by LeeMaster; 04-11-2013 at 07:09 PM.

04-11-2013, 05:32 PM	#27
civicdrivr Senior Member Join Date: Mar 2012 Drives: 2018 Golf R Location: Richmond, VA Posts: 2,807 Thanks: 5,386 Thanked 1,095 Times in 647 Posts Mentioned: 68 Post(s)	The most I've gone on a tank was 392.5 miles, that was 12.46 gallons. I have a heavy foot most of the time. Sent from my Nexus 4 __________________ Parting out HERE

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04-11-2013, 09:04 AM	#18
marcosowns Member Join Date: Feb 2013 Drives: 2014 Lexus IS350 Location: Austin, TX Posts: 72 Thanks: 34 Thanked 12 Times in 11 Posts Mentioned: 0 Post(s)	The gas light is very fool proof. You should very easily go at least another 30 miles after the light comes on if it is necessary. I've had other cars (Honda/BMW) which I have driven a few miles indicating 0 miles left in my tank. Now whether you should be doing that is a whole different discussion.

04-11-2013, 09:15 AM	#19
Mikem53 Senior Member Join Date: Apr 2013 Drives: FR-S 6MT Location: Somewhere in Space Posts: 1,565 Thanks: 500 Thanked 882 Times in 433 Posts Mentioned: 5 Post(s)	In tank fuel pumps are cooled and lubricated by the fuel... Best not to run them too low as they can overheat and fail...

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