pb06

First, thanks to those who offered suggestions when I posted earlier about a cl I was considering. I did buy it, and am very happy with it.

I did'nt relaize, however, till I went to gas up that I'd just bought a premium gas car. Given prices right now, that can add up fast.

My question is: Is 91 octane really necessary? What would happen I used 89, for ex.?

CLsuperhero

Overtime if you use 89 octane you can create pinging in your engine. It's really not good for it and eventually you'll need serious engine work done. Stick with 91 or up. if you go with 89 make sure you always add an octane booster with it.

Acutron

Most def'. Even at this high altitude I still run 91.

resedaruss

iTrader: (1)

In my 2003 owner's manual it states that they recommend premium gas, but it also states that it will run on regular with slightly reduced performance.

In meetings I have attended with research chemists at ExxonMobil Research, it is common knowledge that most engine designers (including Honda/Acura) provide engine sensors that detune the engine as necessary to accommodate the octane content of the gas.

Thus, the power and efficiency of the engine is slightly impacted--but the engine sensors won't allow destructive pinging--the spark is retarded in real-time, as conditions warrant, before that happens.

MarbleGT

you probably wouldnt notice much of a change.

fuzzy02CLS

iTrader: (2)

It's been proven on this board running 87 or 89 while it won't hurt the car, will yeild worse gas milage, & the savings over the corse of a year isn't much at all.
Stick with 91+

MarbleGT

^^ Well said my man.

evilstorm

for the ~$130 you spend more per year it isnt worth to find out.

Lord Helmet

Where in high altitude are you located, Acutron?

CL'er 1st & 2nd Gen's

I would think 91 octane is a must for an S-type, since the compression ratio is 10.5:1

pb06 has a regular CL (non S-type) with a lower ratio of 9.8:1 (same as my plain jane). I have run 2 or 3 tanks of 89 with no noticeable difference. But like evilstorm suggested, when you look at the extra cost over the period of a year, I prefer to stick with the premium.

pb06

Great information. Thanks!

Acutron

Beautiful Colorado Springs!

Lord Helmet

For some reason I knew you were in CO.

CL6

Your engine won't care. Sure, you might get 2 or 3 mpg worse but who cares? I do mostly highway driving and have no problems. Maybe I'm getting 5% less power but seems fine to me. In hot weather or at high altitudes I'd go with the higher octane. 91 is more important for the smaller, higher compression 4 cylinder engines.

pits200

Think about what you said CL6, you said you might get 2 - 3 MPG less. You take that over 15 gallons and that would equal anywhere from 30-40 miles less per tank. Now 1 gallon of gas cost $3 dollars and will net you about 25 miles on that 1 gallon. So lets do the math..

15 Gallons at 3.00=$45.00 gets you about 300 Miles per tank estimate for 91+ octane

15 Gallons at $2.90=$43.50 gets you about 270 Miles per tank estimate for 89 or 87 octane

So you save $1.50 initially, but your losing 30 miles. High estimate 30 miles = 1 Gallon

and 1 gallon = $2.90... So your actually losing $1.40.

CL6

Let's see. 91 is .30 more per gallon than 87 where I live.

Let's say I buy 15 gallons of 91 gas - $4.50 more

Let's say that, over 15 gallons, I get 30 miles less than with 87 (I presently average about 21 mpg) so this is about 1.5 gallons 'lost' per filling. The difference is about .45. However, the difference when I fill-up is $4.50.

So when you subtract the different gas (.45) from my savings (4.50) I come up with a gain of 4.05.

$4.05 x 4 times per month = $16.20 x 12 months = $194.40

$194.40 = 1 month's 'free' gas.

Seems okay to me! (Or did my math go wrong?)

pits200

I was taking a more reasonable comparison. I have 3 levels in my area, 87 89 91, some places carry 93. Each level is a 10 cent jump in price. I was comparing the 89 to 91, I dont think anyone would recommend dropping all the way to the low quality grade. For a high compression car like ours, using 87 consistantly over time will cause problems in the engine. But honestly, think of it, $194.40 seems like a good chunk of change as a lump sum, but when you stretch it out over savings for 12 months, it is like .50 cents per day. Thats the whole concept of credit cards, paying up front and stretching it out over time.... Oh well, good luck

pits200

Wait, you didnt do your math right, I was just thinking about it..... I am an idiot...
Ok,
15 gallons at $3 dollars is $45 bucks
15 gallons at $2.70 is $40.50 plus 1.5 extra gas for the loss is $4.05 more = $44.55
So it only saves .45 cents per FILLUP... Now thats the truth

CL6

Yeah I re-worked the math. Looks like it's a break even situation. Weird thing is I always used 91 but recently tried 87 and I swear the mileage went up with 87 but now is down. I need to do a few fill ups of each back to back and see what my mileage is. I was an English major anyway.

pits200

Its all good, just wanted people to realize that they arent saving much money by going with lower grade gas...

evilstorm

and since we drive an acura, i would hope that we can all afford the extra $150 a year

mefromuic

What's the science behind that? Higher altitude, cleaner air? Higher altitude also means less air density which means less oxygen to the car which means less performance.

Lord Helmet

Maybe someone else can chime in on this to give more info regarding the power loss. All I know is that in high altitude, some cars tend to get better fuel milage. Example: my mom used to have an Eclipse about 10 yrs ago when they moved to CO from FL. once they brought the car out here, it got about 3 more miles to teh gallon. I wonder myself how that works out.

Anyone have the answer?

mefromuic

Someone posted this calculation before but I couldnt find the post to repost it. The point of wanting to use regular fuel instead of premium is to save money but the math shows that it isnt worth the lack in performance (and probably gas mileage) plus the extra wear on engine due to dirt and knock.

An average person drives around 15,000 miles per year. Lets also assume your car on average gets 22 mpg. Divding 15,000 miles by 22 mpg gives your the amount in gallons of fuel you use per year. Which is 682 gallons. Using these current fuel costs, your savings per year would be:

Premium: $3.19 x 682 = $2176
Middle: $3.09 x 682 = $2107
Regular: $2.99 x 682 = $2039

So if you use regular instead of premium you would save about $137 per year. However middle grade fuel at most gas stations is already 91 octane (which is the min the manual recommends) so if you compare it to that you only save $68 per year. If you figure that you will lose mileage becuase of using the regular fuel, that pretty much offsets it's savings. Not to mention regular fuel are dirtier and will build up on your spark plugs and other components further lowering your performance. Octane becomes an even bigger issue at higher rpms. So if you plan on driving like a grandma, you should have gotten a TL! haha, jk.

Also note that if you drive less than 15,000 miles per year and/or get better than 22 mpg, your savings would be even less!

For me, i worry more about the mpg I get on the CL and what i can do to improve it. I've heard mods actually help the mpg. I'm still doing research.

mefromuic

Woops, I only read the first 6 or so posts before reposting.

CL'er 1st & 2nd Gen's

Thinner air = less wind resistance?



With altitude, air density decreases. The computer controlled fuel injection system will automatically decrease the fuel in the mixture to match the air density. You will find that horsepower will decrease, but mileage will actually increase.

Acutron

You out here too Helmet?

mefromuic

Is there a way to control the computer controlled fuel injection system to get better mileage? I'm willing to give up some hp for some mileage.

CL'er 1st & 2nd Gen's

I think you'd have to chip for that. There have many discussions about chipping, though I never heard of anyone getting a chip to de-tune their car.

Try a search. There are alot of threads. Here's one to get you started.
https://acurazine.com/forums/showthread.php?t=177752

Lord Helmet

Castle Rock to be exact. I'm in the Springs on most weekends though. Got some friends down there.

Acutron

No Doubt!

ktgumbo

Its only $3 more per tank. DONT BE CHEAP