But WHY would anyone use a 5w30 in a lawn mower engine in the first place? It’s a hardworking hot running machine so a more suitable grade like 10w30 or 10w40 would be better….
Sounds like the DPF issues were already happening before the improper oil change….however the owner should be able to get some consideration due to the screwup, I would think.
Changed U/K oil to Amsoil 10w40 Premium Protection and NGK Spark plug too. Neighbour cleaning out his garage and I bought this little Honda generator cheap…😉
Amsoil Synthetic Small Engine Oil meets the SG, SH, SJ with high ZDDP that you’re looking for. I use the 10w30/40 in all my small Honda engines.
https://www.amsoil.com/c/4-stroke-power-equipment/12/?zo=331384
All’s well that ends well. But now discontinue your habit of removing the battery at the end of your growing season and simply leave it in, and attach the maintainer.
Unplug, remove, start it up, next season….