1stgenGSb

so im a poor college student, and gas prices are KILLING me. i try to always get premium, but sometimes i just cant afford it, so what am i doing to my engine when i use lower grade fuels?

YupImJOee

from personal exp, my CEL would come on if the car had 87 and it would spit and sputter.

from using 89 i would lose some power but gain a few mpg's.

89 here in san diego is around 4.79 vs 4.89 for 91

so for full tank on 89 it would be about 100.59
for full tank on 91 it would be 102. 69.


you would save 2 dollars. is it worth it?

gs300pnp

knock & run-on is what I've experienced. I changed gas stations and same thing happened. super works fine

Hartawan

iTrader: (1)

yeah going 91 to 89 wont save you that much money. the only way is to carpool with other people or ask them for gas money. or just stay home all day.

kit cat

iTrader: (6)

stop drinking starbucks.

mmarshall

Here is the general rule, without going into all the details:

If your engine was designed for "Regular" or 87 octane, use it. Using higher-grade gas, in most instances, is a waste of money....although premium gas often has more detergent in it to help keep the engine clean. Still, if you use a major name-brand regular, or Chevron or Shell in particular, you shouldn't have problems with deposits and carbon buildup.


If your engine has "Premium RECOMMENDED", you can use regular in a pinch, but not for sustained use. And even if you can use regular, the engine's computer and knock sensor will retard the spark to compansate for the lower octane...so you will be using cheaper fuel but getting less power and poorer gas mileage, and not necessarily saving any money.

If your engine has Premium REQUIRED, there's no choice.....either use premium or risk engine damage and void the warranty.

darkdream

its no point to save like $2-3 dollars on a tank of gas...thats like nothing...
your engine will eventually misfire.. and you will get less gas mileage since the engine was designed for 91 octane, so in the end you will probably end up not saving anything and perhaps damaging your engine...

lobuxracer

iTrader: (2)

I lost 35% of my fuel economy running 91 in my Supra that was designed to run 93. Cheaper gas is a false economy, your mileage will suffer.

whoster

the world will end if you don't go premium.

YupImJOee

my 88 mk3 said to use 87, I went through 3 rodknock stages before someone told me to use 91 on turbo cars.

so sometime its better to use higher octane and sometimes it isnt.

ex.

my old 97' 3.0 CL. I was feelin happy and put in 91, and it ran like ****.

4TehNguyen

iTrader: (1)

regular tank vs premium tank is like what $4 a fill up difference. Stop eating out, try to carpool, reduce uneccessary driving are going to save you a lot more than $4 a fill up. I usually question someones spending habits if $4 a tank is "killing" them. Who knows what its doing to your engine if you start using regular fuel, a repair isnt cheap either. Knocking is very bad for an engine

DustinV

A co-worker of mine has a BMW 118i and he said he could fill his car up with lower-grade-gasoline and the engine would "automatically adjust". Apparently this is what his BMW dealership told him.

Anyone know if this is a feature of modern cars? Seems totally workable.

4TehNguyen

iTrader: (1)

its retarding the timing, but when a car does this you are losing power and fuel economy, possibly damaging your engine, defeating the whole purpose of saving money

Magellan

As a poor college student there are other ways to save money:

• If you’re a smoker, pick up butts from the street instead of buying fresh packs.
• Reuse coffee grinds at home. You can make a least three extra cups this way.
• Pack a few sandwiches if going out on a date.
• Look for loose change in the sofa.
• Put a half-cup of water in your beer.
• When out with friends say you forgot your wallet and let them pay. Then just forget about it.
• Wash clothes in your bathtub instead of using a Laundromat.

But above all, don’t shortchange your prized Lexus on gas.

Stage3

iTrader: (3)

I dropped down from premium to midgrade and haven't noticed any difference in performance. Fuel economy hasn't changed any, so really, it's only a savings of 10 cents for gallon (or $1.60-$1.80) per tank. It's not much of a difference when filling up so it's really not much of a gain. I'll probably just switch back after my 1 month Midgrade experiment.