Is their a serious downside to using 10W40 as opposed to 10W30 in a
2002 TJ as I appear to have a lot more choice of oils at this weight than the 10W30 in full synthetics. I was reluctant to go down to the 0W30 & 5W30 unless anyone has an opinion to the contrary as I do not need that amount of cold weather starting capability.Cheers Nick