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I have MS 170 Stihl that will not start. Model number, etc on photo. I used it yesterday, shut it off, and today, will not start. I replaced the spark plug as the old one had some crud on the ceramic post. I have spark. My gas is the Stihl oil and rec gas about 5 months old. I cleaned air filter, still no fire. I gave it a shot of ether, no fire. So, before I tear into it, any suggestions.

colly43 said:

I have MS 170 Stihl that will not start. Model number, etc on photo. I used it yesterday, shut it off, and today, will not start. I replaced the spark plug as the old one had some crud on the ceramic post. I have spark. My gas is the Stihl oil and rec gas about 5 months old. I cleaned air filter, still no fire. I gave it a shot of ether, no fire. So, before I tear into it, any suggestions.

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Go get fresh gas from the pump, five month old pre-mix is not fresh. Remove spark plug, pour a tiny bit of gas into cylinder, and start it.

If it is a MS170(Z) and not a MS170C then first check the spark arrester screen on the muffler. These clog as Stihl tends to run the engines on the rich side. MS170C uses a catalytic style muffler so no spark arrester.

Btw I use 2 cycle fuel mix as old as two years without problems but it does contain a stabilizer.

Thanks Tiger and Star. I went to the dealer and bought Stihl's Motomix, drained the old gas, filled her up and it ran on second pull. It is a bit pricey, $34/gal, but a lot less trouble than cleaning carbs, etc. I did have Stabil in the gas.
THANKS
colly43

colly43 said:

Thanks Tiger and Star. I went to the dealer and bought Stihl's Motomix, drained the old gas, filled her up and it ran on second pull. It is a bit pricey, $34/gal, but a lot less trouble than cleaning carbs, etc. I did have Stabil in the gas.
THANKS
colly43

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Motomix, Tru Fuel, in other words, canned pre-mix, is both expensive, and not the way to go for 2-stroke engines. It is another somewhat controversial topic. You can do the research if interested. Mix one gallon at a time of gas and 2-stroke oil and you will be fine.

I have never seen a 2 stroke oil that didn't have fuel stabilizer already in the bottle. So no need to add stabilizer.

ILENGINE said:

I have never seen a 2 stroke oil that didn't have fuel stabilizer already in the bottle. So no need to add stabilizer.

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The Stihl synthetic 2-stroke oil does NOT contain fuel stabilizer. Just read it on their site. Just like I recommend to my customers, Stihl says 30-60 days on shelf life for handheld equipment. Keep it fresh and moving, because 2-stroke and 4-mix equipment love fresh fuel.

Tiger Small Engine said:

The Stihl synthetic 2-stroke oil does NOT contain fuel stabilizer. Just read it on their site. Just like I recommend to my customers, Stihl says 30-60 days on shelf life for handheld equipment. Keep it fresh and moving, because 2-stroke and 4-mix equipment love fresh fuel.

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Here is says it doesn't

Q: Hi, been using the old orange bottle stihl oil for years, I recently swithched over to your stihl hp utra oil. Noticed the bottle doesnt say that the oil has fuel stabilizers in it. Does th stihl HP ultra oil contain fuel stabilizers?​

Joedirtbikera year ago
1 Answer

A: Thank you for your inquiry and interest in STIHL products. The HP Ultra does not contain stabilizers.​

But apparrently the old orange bottle does.

Does the 2 cycle high performance oil have a stabilizer?​

Jeanne745 months ago
1 Answer

A: Thank you for your inquiry and interest in STIHL products. STIHL High Performance 2-cycke Engine oil provides superior lubrication and contains fuel stabilizers.​

Customer Care

Buy Stihl 2 cycle oil and mix your own. I bought a measuring syringe that has graduations so you can accurately make small fuel batches down to a pint. That way you mix what you need and old fuel is less of a problem. Stabil breaks down to 1 cc or ml per pint of fuel. One ml is 15 drops, more or less. If you use small 2 cycle machines infrequently, making your own small fuel batches saves you money and stale fuel.