SPINJIM 1,985 #1 Posted August 17, 2022 I'm changing the plugs in on my 418A / Kohler M18 twin. The old owner's manual recommends a Champion RV15YC, but others have recommended the hotter RV17YC. The RV17YC that I'm removing look like they're burnt; maybe too hot. I was going to change to NGK plugs BPR4FS, but NAPA converts that to an NGK 1127. Are the Champion 17 heat and the NGK 4 heat levels too hot? I use the tractor mainly for plowing snow, and sometimes for moving mulch or dirt. What NGK (or Autolite) plug have others used? Share this post Link to post Share on other sites
J854D 139 #2 Posted August 17, 2022 (edited) From my days in the auto parts business most spark plug manufacturers caution not to use interchange lists to select the proper spark plug because the spark plug heat range between plug manufacturers don’t always coincide. It is always best to use a current application catalog to choose the right plug for your application. And discard old catalogs because spark plug manufacturers continually update their recommendations. So just choose which brand spark plug you prefer and use their catalog recommendation. -JD- Edited August 18, 2022 by J854D Added info 3 Share this post Link to post Share on other sites
squonk 43,492 #3 Posted August 18, 2022 (edited) Since the 17's look burnt I would go back to the 15 heat range. I prefer Autolite. # 26 is the equivalent. Edited August 18, 2022 by squonk 2 Share this post Link to post Share on other sites
