My new to me son n law has a 4240 and always has 15-40 wt oil in his tractor during the winter. We get temps down in the teens and minus degs in the part of the country where we live. It seems every year he has issues with the tractor starting during the lower temps. I have been helping him with this issue and I have convinced him to keep a Battery tender on the bats and that has helped.
My question is would 10-30 wt make a improvement with his situation and what about a 5- 40 synthetic as well and he could run the 5-40 all summer also and not half to change oil every season. I stopped using 15-40 in my 7.3 Ford PS and opted to use 10-30 and experienced good results and according to what I read the 15-40 shears down to a 30 wt anyway after some time in the engine.
I'm curious what others are doing in this situation,,,,,and before I forget to add the Bats. and voltage output are good and up to date.