I have had this '01 Jeep Grand 4.0L for a year. I have put just just over 15k on it since bought and I did OC when I got it home with GTX 10w30...then 4k later I did a couple 4k OCI w/ Trop-artic 10w30 blend, and both oil levels with both of those brands dropped some on the dipstick by 4k and that is how I established my OCI for this Jeep. They were also notably darker than the Pennzoil HM. I just got gas and checked the dipstick cause I rolled 4k as I pulled into the station. The Pennzoil HM 10w30 is cleaner looking and has decreased NONE on the dipstick since the last OC. Does this mean I should maybe push it on out and see how it looks at 5k? I generally do not like to top-off so I do an OC when oil goes down even slightly. My next oil in the hole waiting to be tried is Max-life 10w30 blend. But I am impressed with the Pennzoil and how the Jeep sounded & ran with it + the facts mentioned above. Thoughts? The Jeep has 80,4xx on the ticker right now.