Got an older Craftsman lawn tractor that has had a diet of 10w/30 mobil 1 changed at 40-50hr intervals. It is the V Twin 725cc engine - good engine for sure! Anyhow, my son thought he heard rod knock and was worried. I listened and heard it too - it was bad so we did a quick oil change and this time put in Mobil 1 V-Twin 20w/50 that I use on the Harleys . Rod knock was still there - but it turned out to be the steering linkage loose and hitting the crank pulley making the noise.... So we are actually ok thank goodness! With that - would you guys leave the 20w/50 in there? I personally think it will be ok especially in Texas but I also know 10W/30 is the recommended oil.