Brother got a Jeep Liberty with the 3.7L V6 Engine, no idea what it had in it before but it leaks a little bit of oil. Going to do an OC and thinking of throwing in MaxLife 10w-30 or maybe 10w-40 with a Fram Ultra and see if it stops the leak or slows it down. I'm sure he will get it looked at eventually, but I'm just wondering if there will be any harm doing the 10w-40 even though its specced for 5w-30/10w-30?