This will be a somewhat long and meandering post. My fiance's car is a 1998 Olds Intrigue. It has 160,000 miles on it now. It was her grandparents car and well maintained by her father, a GM mechanic. It was on 3k OCI's until 130K w/ Dino oil. I have since been doing OCI's at 5k w/ one quart of M1 5w-30 and 3.5 qts Exxon Superflo (which I have over 6 cases left that I scored at .69 a qt. in fall of '05). Well of course her g'pa was outraged by the 5k interval. Dad is kosher with it. I don't really plan on changing this, but wonder what everyones thoughts are on this? Most of the miles are easy highways. Since I've switched, the car uses at most, 1/2 qt. of oil. Thanks ahead of time. I am really just interested in peoples opinions. Thanks.