Spark Plugs Fouled @ 75 Hours

[SeniorCitizen]

I've ran Briggs engines for years and usually the plugs last that long also, but I have a Briggs engine in a new purchased John Deere LA 135 LE that has fouled the plugs around 75 hours twice in its 150 hour life span.

I know when to replace them because of the sputter, pop, fart, banging and very bad exhaust smell. The only additive I use is about 1/3 the recommended amount / instructions on the container of Marvel Mystery Oil in the gasoline. The gasoline I buy for it is 92 octane and has no indication of containing alcohol on the pump. It definitely does not sip gas. Any ideas to correct the problem or is this standard for our new non polluting engines.

The usual recommendation is a hotter plug and a different brand but I would think John Deere would know what plug to use in their engines. Any other ideas ?

Briggs 22 HP OHV
Engine Mod. 407777
Type - 0188 B1
Code - 080125 YG

Spark plugs - Champion RC12YC

 

[EngineMan]

Renew the spark plugs/engine oil, stay away from the additive, and see what you have in the next 75 hours service, if its not burning engine oil its the additive.
I will not use any additives in anything.

http://www.amazon.com/Champion-Spark-Plug-CHAMPION-RC12YC/dp/B001UFQCH4

 

[Rivets]

Agree with EngineMan on this one. Never found an oil additive for a small engine that did more good than harm. Also, what weight of oil are you using. B&S recommends straight 30 W.

 

[RobertBrown]

You didn't mention if the plug had the correct gap. Check the gap
The lower octane gas burns / ignites faster. Skip the additive and go with 87 octane.
See if that helps, and you can save enough money to get some better plugs, look for NGK or Bocsh.
You will never have to change them.

 

[SeniorCitizen]

Using 30 wt. oil. MMO additive and gas from the same can is in the old Murray with a 12 hp Briggs and the plug hasn't been changed in years. Yes, the 12 hp briggs does run and does a fine job.