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STIHL GUY
05-21-2008, 09:21 PM
I have a Stihl stick stimmer and a leafblower and i have been running them with 87 octane gas. Is this OK or should i use 89 or 93?

billslawn89
05-21-2008, 09:24 PM
thats what i use, but the oil i use is the synthetic. i've read other lco's uses the higher grade. i've had no problems thus far.

Precision Lawns
05-21-2008, 09:43 PM
I use 93. Just always have.... This post may make be rethink this.....;)

BillyRgn
05-21-2008, 09:49 PM
i have neer run anything but 87

BillyRgn
05-21-2008, 09:50 PM
ment to spell ->never*

cgaengineer
05-21-2008, 09:59 PM
87 for me as well. I think I ran 1 tank of 93 when I first got the Stihls but after that its 87 for everything.

jkason
05-22-2008, 09:05 AM
If you check the OWNER'S MANUAL, it states that you need a minimum of 77 octane.

Why spend more than you have to on fuel?

DA Quality Lawn & YS
05-22-2008, 09:50 AM
Per below, agreed.
Why spend more already supremely overpriced fuel.


If you check the OWNER'S MANUAL, it states that you need a minimum of 77 octane.

Why spend more than you have to on fuel?

topsites
05-22-2008, 10:00 AM
Because premium's 4 bucks even and this makes the math easy. :p
I run premium in everything, I don't even question this.

dballs
05-22-2008, 10:25 AM
My Stihl blower manual says minimum octane of 89. I wondered if 87 would hurt it too but just decided to stick with the 89 to be safe.

44DCNF
05-22-2008, 11:20 AM
My Stihl blower manual says minimum octane of 89. I wondered if 87 would hurt it too but just decided to stick with the 89 to be safe.
The Stihl manual you refer to probably says 89 ROZ or RON correct(European)? Converted to our system of rating octane in the states, it equates to 87 pump octane.

Bennett scape
05-22-2008, 11:35 AM
87 octane is fine for most engines. The octane rating is a rating of the anti-knocking effect of the fuel source so 87 octane has a 87% anti-knocking rating. knocking is just auto ignition or when the engine automatically ignites the fuel when it is not suppose too in its cycle this for a spark ignition engines, diesel engines have a different rating called Cetane. Also an octane rating does not indicate the energy value of a fuel source that is something called a heating value. Octane is only a measure of the fuels resistance to auto ignite. :)

dballs
05-22-2008, 11:58 AM
The Stihl manual you refer to probably says 89 ROZ or RON correct(European)? Converted to our system of rating octane in the states, it equates to 87 pump octane.

Actually it states "Use mid-grade unleaded gasoline with a minimum octane rating of 89 (R+M/2). If the octane rating of the mid-grade gasoline in your area is lower, use premium unleaded fuel."
Stihl BG 55, 65, 85, SH 55, 85 Manual page 13 FUEL

http://en.wikipedia.org/wiki/Octane_rating
indicates R+M/2 is the US measure
"in the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2."

From that information, it appears that Stihl is recommending 89 US octane, but I could be mistaken.

44DCNF
05-22-2008, 12:14 PM
Actually it states "Use mid-grade unleaded gasoline with a minimum octane rating of 89 (R+M/2). If the octane rating of the mid-grade gasoline in your area is lower, use premium unleaded fuel."
Stihl BG 55, 65, 85, SH 55, 85 Manual page 13 FUEL

http://en.wikipedia.org/wiki/Octane_rating
indicates R+M/2 is the US measure
"in the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2."

From that information, it appears that Stihl is recommending 89 US octane, but I could be mistaken.


You are correct then. Someone recently quoted a manual that listed ROZ first, and they were going by that higher number and choosing premium at our pumps thinking they needed to. I just wanted to make sure you weren't using the wrong rating system. Thanks for the clarification.

Den69RS96
05-22-2008, 12:32 PM
One way to increase hp is to raise compression. However raising compression increases the heat. To much heat and you have pre ignition, knock, denotation whatever you want to call it. Thats pretty much how diesel engines work as they don't have spark plugs. Diesel engines run really high compression ratios. In the hot rodding world, a lot of people switch over to aluminum heads since they get rid of heat faster allowing a little bit more compression than cast iron heads. Another way to combat pre ignition is to ****** your timing. However most older cars and lawn equipment don't have knock sensors or computers to sense knock and ****** the timing when that occurs. Most modern cars do, so thats why you see new cars using 87 but make some decent horsepower. Another way to combat this is to use higher octane gas which takes longer to burn. The higher the octane number the longer it takes to burn. If you put to much strain on a engine while using a low octane gas, you could put a nice hole in your piston. I'm not saying this is going to happen to some running 87 when it calls for 89, but if the conditions are right there is the potential to damage your engine.

Charles
05-22-2008, 12:40 PM
87 octane will shorten the life of the piston. I learned that the hard way when I first got into the biz:rolleyes:

SamTheLawnMan
05-22-2008, 03:26 PM
Check this out....Long acticle but I found it interesting.
http://finance.yahoo.com/family-home/article/105077/6-Gas-Saving-Myths

frogman18
05-22-2008, 09:35 PM
Always 93 in anything 2-stroke here

ProStreetCamaro
05-22-2008, 09:50 PM
We had an engine blow under warranty on a Fradan backpack blower once. Our friend sold power equipment and we needed a new blower and he showed us this fradan. It looked good and we tested it out and it was powerful so we took it home.

Well we always use 87 in everything with no problems. After a year the engine let loose so we took it to him to look at. He tore it down and showed us where the connecting rod had been pounding into the crank. He told us thats from running 87. It was detonating and after a while it finally fatigued and broke. He replaced the short block and we ran 89 and never had another problem out of it.



EDIT: As a matter of fact it was this exact blower right here.


http://www.fradanpower.com/images/thumbs/bb51-2.jpg

tamadrummer
05-22-2008, 09:58 PM
93 in my 2 stroke and 89 in my mowers.

dgfitz
05-23-2008, 05:08 AM
The Stihl manual you refer to probably says 89 ROZ or RON correct(European)? Converted to our system of rating octane in the states, it equates to 87 pump octane.

The ealier
Stihls that were produced used the
european formula, the newer ones manufactured in the US
use the US formula of 89 oct, because, as told to me by a
Stihl rep, they have to run leaner for US emissions, and
the 89 oct allows the equipment to last longer.

Swampy
05-23-2008, 07:37 AM
We also learned the hard way using 87 oct with 10% ethonal = bad. Went threw about 3 stick trimmers, 4 hedge trimmers, a back pack blower and a brush cutter. Now we spend the time to just run out of the county to get 89 oct with out the ethonal.

tallimeca
05-23-2008, 01:11 PM
89 minimum octane. Manufacturers tell you to use that for a reason and it isn't because they are making profits off the gas prices.

Furthermore, i've seen more failures on Stihl equipment using 87 then any other equipment out there for some reason. Im' not bashing Stihl by no means. They recommend 89 and if you dont' use it, it's not their fault, however, they say it for a reason and i've seen the reason.

87 octane doesn't mean you just get a little less performance then if you were using 89.

It means you won't be melting your pistons and rings.

I common misdiagnosis of 2 cycle engine failure when you see scoring is.......lack of oil in the fuel.

The reality is no, there could have been plenty of oil, the engine simply overheated which causes the rings to get stuck, catch the edge of a port, gual, the run it up and down your cylinder wall, which in turn rubs on the piston skirt and it's good night irene.

Also 87 has less detergent, which is a big part of the reason they don't want you to use it on a high heat, high rpm, air cooled engine. The higher octane fuel helps keep the engine cleaner from deposits. The higher octane, the more likely the fuel is to not combust under heat. With 87, the engine gets hot spots on the cylinder and piston. The fuel comes in and fires off before the spark plug fires. These hot spots are moulten metal...which make the top of the piston look like the surface of the moon. See below.

I had a guy come in with a chainsaw a few weeks back. Top of the piston looked like i was hitting it with a welder, all mangled with holes and melted crap. I asked him if he was using 87 and he said yes. I asked him if he thought there was any reason why i have a big sign on the handheld display telling customers not to use 87. He said he has always used 87 and never had a problem.

My answer was, well, there's a first time for everything. My calculations are that the failure on this saw made the 10 cents a gallon savings on his last 3000 gallons of gas a break even.

So lets say (hypothatically....opinons vary) the avarge crew of a mower, trimmer, blower, saw cutting say 5-6 days a week is going through on average 30 gallons of gas a week, that's 100 weeks. Most LCO's up here are only running 8-9 months out of the year, so that's maybe 3 seasons.

So you could look at it as, well, if this say hadn't failed, over 3 seasons, that's 300 bucks in my pocket, which is true. However the saw did fail. And, I know this customer HAS HAD other 2 stroke engine failure becaue i have sold him replacement trimmers and blowers, but he probably didn't know WHAT WAS causing them to fail, but just knew they were dead because they were 2-3 seasons old.

The reality could be they may have lasted another 2 seasons had he been using 89 octane, rather than 87 ocatane. So if he bought say a back pack for 500 bucks and a trimmer for 300 bucks, the savings on the fuel didn't exist and it did infact COST HIM MORE........???

Just some food for thought. Some guys don't look at things from all angles. The manufacturers and dealers aren't getting rich of gas prices. They are feeling it the same as anyone else out there.

jkingrph
05-23-2008, 01:45 PM
If you check the OWNER'S MANUAL, it states that you need a minimum of 77 octane.

Why spend more than you have to on fuel?

Never seen a 77 octane. mine says 89, but 87 seems ok.

qualitylawnlc
05-23-2008, 09:27 PM
I run 87 in everything. All handheld equipment is Stihl and no problems. I do use ProBlend synthetic blend 2 cycle oil, though. This combination is all any of them have ever had in them.

alphaboy1
07-05-2009, 11:47 AM
Is it OK to run middle grade unleaded fuel in a Bobcat Hydro? It appears to run smoother but would be interested to hear from others.

Thanks

DaddyRabbit
07-05-2009, 01:59 PM
93 octane rating or bust. You just can't fix cheap!

bighaydenslawn
07-05-2009, 05:44 PM
I run 89 in my mower.

I run 89 and Stihl HP Ultra 50-1 in my handhelds.

metro36
07-05-2009, 05:52 PM
I run premium (93) in everything. It is only a little bit more but it is much better for the engine. I want to get the most life out of my equipment I can so I dont think twice about it.

GreenmanCT
07-05-2009, 06:06 PM
87 in the mower all day long.....as for my stihl fs90 and br550...i use 89 and the stihl mix for those, everything runs great..

Running premium in your mower is simply pointless, these engines werent designed for higher octane fuel. Go ahead an spend the extra money. def stay 89 on the 2 stroke though.

GravelyNut
07-05-2009, 08:36 PM
The other reason for using 89 is that any oils added to the gasoline tend to knock the octane rating down a couple points.

And the formula for pump gas octane rating is (R+M)/2 which stands for Research + Motor / 2. Research is a variable compression test engine running at 600 RPM and Motor is the result of using a variable timing test engine running at 900 RPM.