I bought a motor with unknown miles the 120k was just done but no crank seal. I read synthetic might mot be good for our motors with a lot of miles on them. Should I do regular 10-30 or synthetic? Also I live in ny and winter is coming should I keep 10-30 or go to 10-40? Thanks
Follow Ups
Synthetic fluid or no? - Diplomat116:13:07 09/19/15