Octane Question.

[1 SX]

I have heard, for where i do not know, (maybe i even had a dream... ) i cant remember, but i thought someone said that using higher octane for small engines, can damange them. I use 93 Octane for the craftsman 3.75HP 2004 Power washer, Craftsman 2004 18.5HP B&S tractor, Craftsman 6HP Push lawn mower 2008, and even for the chain saw, leaf blower... Am i damaging the Engine?? Thanks!

 

[ARB1977]

No...my wifes uncle uses 93 in his honda lawn mower. I tried 93 in mine, for some reason it didnt like it. Back to 87 with FP Plus...runs great. All your doing is burning a hole in your wallet.

 

[JTK]

 Originally Posted By: SL2

.. i thought someone said that using higher octane for small engines, can damange them.

Nah.. It won't do anything but further damage your wallet. Joel

 

[dwendt44]

I have heard that a steady diet of high test will carbon up an engine designed to run on 87.

 

[Turk]

I run 100% gasoline 92 octane in all my small engines for years - no issues whatsoever!

 

[ViragoBry]

The manual for my 6.5hp Briggs states absolutely no octane over 87. I can't imagine why you'd use anything else. Seems like a fuel that resists detonation would be harder for a small engine to burn.

 

[tmorris1]

I don't run it for the octane. The 92 Octane is the only stuff you can get around here without ethanol in it. I will use ethanol during June/July when I mow a lot so it gets used up fast, but I don't like storing engines using it.

 

[RWEST]

 Quote:

I will use ethanol during June/July when I mow a lot so it gets used up fast, but I don't like storing engines using it.

Excellent point!!

 

[IndyIan]

91 Octane is what I use in my small engines because: 1. It normally doesn't have ethanol 2. My 372xp chainsaw requires atleast 89 octane 3. I don't have to worry about old 2 stroke mix (within reason) 4. It allows a bit of safety margin for an engine running to lean before I notice it, less chance of preignition. 5. The gas might end up in my YZ250 6. Gas is the cheapest part of using most small engines, how many engines have you used the purchase price in gas? Even in used equipment its hard to run $50 of gas through it, or $55 if you use premium. I guess if all you use are 20hp/L Briggs then you don't have any real reason to get anything better than 87. I think good gas is just cheap insurance, plus I don't have to keep track of different octanes in my shed. Ian

 

[Pete591]

using 1 91 octane is okay...93 is too high for me. Who sells non-ethanol gasoline these days?

 

[tmorris1]

 Originally Posted By: Pete591

using 1 91 octane is okay...93 is too high for me. Who sells non-ethanol gasoline these days?

In MN all gas has ethanol unless it is specifically marked on the pump. There are a few stations around here that have a premium pump that has a sticker that says No-Ethanol (For use in off-road, small engines, classic cars, etc).

 

[Crashbox]

It may have been true back when "ethyl" was 100+ octane because of the high tetraethyllead content- I can remember as a kid seeing my dad's mower smoking like a fogger when he accidentally put high-test in it. I run about 30% toluene in my first tankful of mower gas for the year and that much will boost the octane rating somewhat with 92-octane premium to start. I do not think it would hurt much today. Just my opinion.

 

[IndyIan]

 Originally Posted By: Crashbox

It may have been true back when "ethyl" was 100+ octane because of the high tetraethyllead content- I can remember as a kid seeing my dad's mower smoking like a fogger when he accidentally put high-test in it. I run about 30% toluene in my first tankful of mower gas for the year and that much will boost the octane rating somewhat with 92-octane premium to start. I do not think it would hurt much today. Just my opinion.

30% toluene in your lawnmower? You must be able to run around your lawn without bogging the motor! I imagine it isn't too good for you though, as mowers aren't really famous for their complete combustion abilities. I've thought about using it for my autocross races but I've heard the exhaust smell is quite noticable... Ian

 

[1 SX]

Okay, well, thanks for the replies, I guess it really does not matter, I will keep using 93 Octane, non-ethanol.

 

[tdi-rick]

here, the high octane fuels have detergents and no ethanol so you end up with less carbon, so I run it, even in my old Briggs.

 

[Crashbox]

 Originally Posted By: IndyIan

 Originally Posted By: Crashbox

It may have been true back when "ethyl" was 100+ octane because of the high tetraethyllead content- I can remember as a kid seeing my dad's mower smoking like a fogger when he accidentally put high-test in it. I run about 30% toluene in my first tankful of mower gas for the year and that much will boost the octane rating somewhat with 92-octane premium to start. I do not think it would hurt much today. Just my opinion.

30% toluene in your lawnmower? You must be able to run around your lawn without bogging the motor! I imagine it isn't too good for you though, as mowers aren't really famous for their complete combustion abilities. I've thought about using it for my autocross races but I've heard the exhaust smell is quite noticable... Ian

It certainly does seem to have more "oomph" on 30% toluene, that's for sure. I also make sure there's FP3000 in the tank for lubricity. The main reason I run the toluene is an attempt to de-varnish anything in the fuel system, whether it helps I don't know but I do like the smell of it.