I just started using Mobil 1 High Mileage 10w-30 in my 98 Civic. Mobil claims it cleans up the motor and recommends shorter oil changes as the clean up progresses. It's on their website. Maybe Mobil has bit of ester in that HM oil? Maybe not? Maybe Mobil 1 HM is the best HM oil for cleaning - might be hype but regardless it seems to be a solid oil even if it is a synthetic.
"....For engines where heavy deposits and sludging exist, we recommend short initial oil change drain intervals of 3,000 miles as cleanup progresses.
It would not surprise me if Auto-rx works faster than M1 HM. I've used Auto-Rx on 3 of my vehicles. My 2 Toyota trucks are still in process since they are not driven much during the winters.
"....For engines where heavy deposits and sludging exist, we recommend short initial oil change drain intervals of 3,000 miles as cleanup progresses.
It would not surprise me if Auto-rx works faster than M1 HM. I've used Auto-Rx on 3 of my vehicles. My 2 Toyota trucks are still in process since they are not driven much during the winters.