93 octane

[dawgdr93]

I have a 2000 coupe with 50,000 miles. I have always run the 93 octane gas as the manufacturer suggests, however am wondering if this is necessary. Do any of you run regular 87 octane gas? IF so, is there any detriment to the engine, decreased mpg, etc?;help

Also, does anyone know what I should expect to pay to change the oil pressure sending unit?

Thanks for your help.
Mike

 

[shark454]

I use 93 Mobile because is saves money. I get better gas mileage using 93 over 89 octane. The better gas mileage more that makes up for the increased cost.

 

[warren s]

You can run 87 octane without any damage to your engine or any other systems.

The differance will be a loss in power as compared to running 93 octane. The computer will retard the timing and all of the other related fuel and ignition settings. If you get on the gas you may notice it feels less responsive.

I had to fill up with 87 once and didnt get any worse mileage than with Sunoco Ultra 94 octane. I also didnt go past maybe 1/4 throttle the entire tank.

Prices are all over the map to change the OP sender -

 

[gmjunkie]

I run regular 87 octane Chevron or Texaco in all my Vehicles that have a Brain!!!

http://www.corvetteactioncenter.com/forums/showpost.php?p=899060&postcount=12

 

[Chemdawg99]

You should only run 87 IF and only IF nothing else is available and not put it in on a regular basis.

 

[DRTH VTR]

I run regular 87 octane Chevron or Texaco in all my Vehicles that have a Brain!!!

I suggest serious thought before you take any advice from this man!

 

[Chemdawg99]

Come on guy's, lets get back to basics. It is a well documented fact that octane is only an anti-detonition additive, and has absolutely nothing to do with efficency or gas mileage. If you are running a high enough compression, you will need higher octane, or you will get detonation. Some cars have electronics to detect this and retard the timing, but this is not how the car should be treated. Detonation breaks piston rings and piston lands, which ruins you week if you have forged pistons and wrecks your entire engine if you have hyperutectic pistons (hope I spelled that one right!). If you are not having detonation problems, save some cash and run lower octane. If you do get detonation, save a lot of cash and run the correct octane. If the manufacturer says to run a certain octane, there is a reason for it, so you really need to do it. If you are getting better mileage on the higher octane fuel, there is something else in it as an additive, but it is not the octane.

You are correct about octane level being an anti-detonation blend. The LS-1 has a 10.1:1 compression ratio (high compression) It has knock sensors that detect potential detonation and pull timing in order to retard or prevent knocking (detonation). Because of this feature, yes, can run gas at an octane level lower than 91 IF you need gas in an area where 91 is not available (there are many rural areas that don't have 91 available). However, this is not meant to be a long term solution to high gas pricesotfl

You can run 87 in your C5 if you don't care about performance. If you have ANY kind of real power mod (headers, S/C, H/C swap, etc....) then you have to run 91 or better NO MATTER WHAT!!!

I don't mean to sound snobbish here, but IMHO, if you can't afford to run 91 or better in your Vette then just go ahead and trade it in for a Cobalt:bash

 

[shark454]

These engines detect detonation and when detonation is detected, the timing is retarted ( that sounds wierd) to stop the detonation. If you use higher octane, the engine will run with more advance and you'll get better performance.

 

[Chemdawg99]

All you need to know about this subject....

From my owner's manual:

Fuel​

Use of the recommended fuel is an important part of the
proper maintenance of your vehicle.​

Gasoline Octane​

Use premium unleaded gasoline with a posted octane of
91 or higher for best performance. You may also use
middle grade or regular unleaded gasoline rated at
87 octane or higher, but your vehicle’s acceleration may
be slightly reduced. If the octane is less than 87, you
may get a heavy knocking noise when you drive. If this
occurs, use a gasoline rated at 87 octane or higher
as soon as possible. Otherwise, you might damage
your engine.​

I don't know about you folks that wish to run an octane lower than 91, but I like my performance, which comes from keeping my Vette properly maintained which means running 91 octane or better

 

[ScottNoxid]

From my owner's manual:

Fuel
Use of the recommended fuel is an important part of the
proper maintenance of your vehicle.
Gasoline Octane
Use premium unleaded gasoline with a posted octane of
91 or higher for best performance. You may also use
middle grade or regular unleaded gasoline rated at
87 octane or higher, but your vehicle’s acceleration may
be slightly reduced. If the octane is less than 87, you
may get a heavy knocking noise when you drive. If this
occurs, use a gasoline rated at 87 octane or higher
as soon as possible. Otherwise, you might damage
your engine.​

I don't know about you folks that wish to run an octane lower than 91, but I like my performance, which comes from keeping my Vette properly maintained which means running 91 octane or better

This has been the be best informed group of guys i have seen answer in a thread in a long time. Except for one???? He would probably run snake oil in his supercharged speed racer, and tell you it is fine:confused he has a funny looking helmet on in case of wrecking. So be careful who you choose to listen to. Do what I do. Go to the pump, and pick out the 93 octane and close your eyes while filling, and you don't know how much you are spending, it's painless.

 

[LLC5]

If you use higher octane, the engine will run with more advance and you'll get better performance.

And miles per gallon. I ran five tank fulls of 87 octane as a test on the Vette, and highway mileage went down 2-3 mpg, dividing miles by gallons, not using the dic. I did a "just had to find out for myself kind of thing" (even though I was pretty sure what the results would be). Retarding the timing (as in using 87 octane, but there are other reasons it can happen) in these vehicles affects both power and miles per gallon. I did this same test in my Subaru which recommends premium fuel, and the results didn't change (same mpg with 87 and 93), so it is vehicle dependent

 

[warren s]

With regard to some of your comments, I stand behind my statements that 1) if your engine requires a higher octane to prevent detonation, you must use it,

Who said it requires a higher octane to prevent detonation? It requires 92 or better to meet the manufactures specifications for rated performance.

and 2) if your engine does not require a higher octane fuel to prevent detonation, you are wasting your money on it.

There are many factors that influence detonation. An LS1 can handle 87 octane with out self destruction. It’s not a 13.1 race engine that needs 45 degrees of advance just to idle. Running on 87 is well with in the range of the ECM to control and allow normal operation with out damage. Normal being reduced power.

Octane has no relationship to increased mileage or better fuel burning. You can say if you burn a higher octane, you can increase your engine timing and get better mileage, and if there is a problem, your engine's computer will simply retard the timing to prevent damage is not only risky but foolish. You all will be easy to identify, you will be the one's retiming your engine at the gas pumps between fillups, or calling AAA for a tow.

So I guess anyone who did run 87 in their LS1 equipped C5 with no ill effects is just a liar or extremely lucky??? Do you even have a C5 Corvette? Did you ever use or see LS1 edit? Or auto tap? Do you have any idea how much control the ECM really has ? Did you ever see what goes into a “Tune” ALSO – remember that most gas stations use the same pump for multi grades of gas, so if the guy before you filled up on 87, and you roll in ands select 92, the pump still has up quite a bit of 87 to dilute your 92.

 

[warren s]

I know all the reasons current engines handle weaker fuels better, computer controls, reverse flow engine cooling, aluminum heads, spark knock detection systems working with ignition retarders, none of which are a single variable to the guy driving down the road between fillups

Actually every one of them is a variable, at more than 60 times per second for evey moment your C5 is running. That the whole point here as to why 87 wont blow your LS1.

I also know that 98% of the people taking your distorted advice will not understand a single thing you are saying, but will fill up with 87 octane instead of what the are suppose to and chance wrecking their engine. No, someone running 87 octane in their LS1 with no ill effects is not a liar, but if the manufacturer says they should be running 89 or better, they may just be lucky.

Reading comprehension issue here. The OWNERS MANUAL clearly states : Use premium unleaded gasoline with a posted octane of 91 or higher for best performance. You may also use middle grade or regular unleaded gasoline rated at 87 octane or higher, but your vehicle’s acceleration may be slightly reduced.

It doesn’t say you MUST use 91 or higher or risk damage…

What year C5 do you have? Maybe your manual is way different than the one for my 99....?

Or is the GM also giving out distorted advise?

 

[DRTH VTR]

OK, guys. We have no new information here. You have both made your point.

 

[warren s]

Its all good -

I wouldnt even think of putting 87 in a car with less computing power than a nuclear sub from the 80s.

My 12.5 to 1 cr, 455 powered 70 GTO would have blown a hole in a piston on the ride back form the gas station.

 

[minifridge1138]

Lets go back to the original Post:

I have a 2000 coupe with 50,000 miles. I have always run the 93 octane gas as the manufacturer suggests, however am wondering if this is necessary. Do any of you run regular 87 octane gas? IF so, is there any detriment to the engine, decreased mpg, etc?;help

Also, does anyone know what I should expect to pay to change the oil pressure sending unit?

Thanks for your help.
Mike

Here is a quote from the 2000 Corvette owner's manual:

Fuel
Use premium unleaded gasoline rated at 91 octane or
higher for best performance. You may use middle grade
or regular unleaded gasolines, but your vehicle’s
acceleration may be slightly reduced.
It is recommended that the gasoline meet specifications
which have been developed by the American
Automobile Manufacturers Association (AAMA) and
endorsed by the Canadian Motor Vehicle Manufacturers
Association for better vehicle performance and engine
protection. Gasolines meeting the AAMA specification
could provide improved driveability and emission
control system performance compared to
other gasolines.
Be sure the posted octane for premium is at least 91
(at least 87 for regular). If the octane is less than 87,
you may get a heavy knocking noise when you drive.
If it’s bad enough, it can damage your engine.

A few points:
1) Chevrolet's recommended fuel octane is 91, not 93. So anything above 91 is burning your money even faster.
2) It says you can use 87.
3) Running 87 may reduce acceleration. That is because the engine will detect that you're using 87 (and any spark knock being caused) and retard the ignition timing. Retarding the timing, will make spark knock go away. No spark knock means that you will not damage your engine.
5) Enjoy the drive.

 

[Chemdawg99]

Lets go back to the original Post:

I agree with your post, put just have a comment or two to add.

Here is a quote from the 2000 Corvette owner's manual:


A few points:
1) Chevrolet's recommended fuel octane is 91, not 93. So anything above 91 is burning your money even faster.

While the above is true, in some areas, only 93 is available and the price difference between 91 and 93 is negligible

2) It says you can use 87.

Very true (I posted this part of the owner's manual earlier) but why????? (see next part of post)

3) Running 87 may reduce acceleration. That is because the engine will detect that you're using 87 (and any spark knock being caused) and retard the ignition timing. Retarding the timing, will make spark knock go away. No spark knock means that you will not damage your engine.

While you may not do any damage, this is NOT a good thing to do in the long run if you care about your C5 I don't care what someone does with THEIR C5, but I will run 91 or better


5) Enjoy the drive.

You'll enjoy the drive even more if you keep your C5 properly maintained (proper maintenance includes running the recommended octane of 91 or better) Just because you CAN do something doesn't mean you should

Again, if you can't afford to run premium gas in your C5, then maybe you should consider another car......

 

[LLC5]

I run regular 87 octane Chevron or Texaco in all my Vehicles that have a Brain!!!

http://www.corvetteactioncenter.com/forums/showpost.php?p=899060&postcount=12

Hey Junk, I just clicked on your attachment, how the heck did you get 35+ mpg with 87 octane? I never got more than 32 with 91-93 octane in my area, and a lot less (28-29 mpg) with 87. That's impressive. You a relative of Smokey Yunick or something?

 

[gmjunkie]

You a relative of Smokey Yunick or something?

No,Ralph M. Jones(Farmer),Charles W. Anderson Sr. (Machinist,Fabricator)and Charles W. Anderson Jr (Machinist,Fabricator,Radiator Repairman and Electrician)!!First two being my Grand Daddy's,and 3rd being My Daddy,always stressed to my brothers and I was,"Everything has a Sweet Spot" (Where everything just Sounds, Feels Right and Runs with the most Efficiency!)!!Don't matter if it's a Farm Implement,Car,Truck,Motorcycle or Woman, Every one is a little different,but Find it and you'll have a Less Stressful,Low Maintenance Life!! "If it's got Teat's or Tires,There's always going to be Problems and Expense,But there ain't no need in causing more of it for yourself"!!
When we were young (7-17) I can't even beguine to remember how many times my Grand Dad Jones came to the field and got on us boys for not driving his tractors the way he liked,He could tell by the sound of each of his tractors from 3/4 mile away if any one of us or all of us hadn't found the SWEET Spot!! Didn't matter if we were plowing,disking or cutting and bailing hay!!

Now you being a Master Technician should kinda understand just what I'm saying!!

In all honesty thats the best I've ever done on a long trip,(usually around 32-34) and yes I check every once in a while with a calculator on the road between fill ups!!(Never found the DIC off more a tenth or two one way or another between fill ups or 4-6 tenths over the whole trip!!)

Now about how I do it with 87 octane,It's purdy simple,I've found the "Sweet Spot" and I run with it!! I don't wring it out through the gears allot,I use 1st-3rd-5th allot and don't run it through all the gears,I set the cruse on the open road between 79-82 MPH in 6th depending ("Sweet Spot") on where I'm at and traffic!!And I won't put gas with Alcohol in it if I can keep from it! I use Chevron or Texaco 1st,Shell or Exxon/Mobil 2nd, BP or Phillips 66 3rd!! (I've got a case of the Azz at Phillips 66 right now,I got some alcohol in Missouri from a pump that wasn't Labeled!!) It Run like Crap and the gas gage quit in less than a 100 miles!! I had to Tectron the heck out of it!! If I pull in and the pump says it has Alcohol.I either go across the street or put a little 89 in it depending on how low I ran it!!

Most people won't give the the ECM a sporting chance to get things right with the change in Octane!!:W:WThey'll be goosing on it here and there to see if the ping is still there or if the acceleration is off or just whatever!! It just makes things just take longer,the ECM will make more changes than just the timing over a little time!! My better half can get in anything and knock my average down from 15 to 25 % in 100 miles or less and says that her driving habits has not a thing to do with it!!
She always complains on how much gas her 4.3 Jimmy uses,"oh it only gets 16-17.5 MPG!! Well it's her driving habits!! I drove it from here to Louisville Ky to DarkSharks, picked up a Complete C3 Exhaust System in one piece!!(from the manifolds back to the Mufflers) Strapped it to the rack on top and drove home,Averaged 21-22 ROUND TRIP!!

PS Every Vehicle will be a little Different,but they all have a "Sweet Spot" where Everything Just Sounds Right,Feels Right and Will get the Best Efficiency and Least Ware and Tear on the Drive Train!!!

Women,I haven't a Clue,I'm on my 4th one and there won't be a 5th!!!

Don't get me wrong,I boot them in the butt once in a while,But I don't beat them!!! :cool

 

[LLC5]

Well said, and yes, I do understand what you are saying. There is no substitute for "been there done that" experience. Driving habits are huge in mpg averages, I guess I will have to try harder. The ECM has many ways to deal with detonation, retarding the timing is just one way. Modern ECM's can also learn driving habits and can adjust accordingly (adaptive logic). I like your honesty about the woman part, a smart man never admits to understanding, even if he thinks he does. I was kind of hoping for a good "Smokey Yunick" story though......