Which oils are better for let's say 2 or 2.5 years oil change intervals? Assume 2-3K miles a year, no short trips and good fuel. Please let's forget about changing the oil once a year ... I am basically interested in knowing what makes one oil better than other for extended time. Are the extended mileage oils also better for extended time? what can make one oil more suitable than other for example does TBN matter for extended time intervals? Thanks!