On my first go round I used the 3M method involving polishing compound and 3-5 different polishing discs. Outcome was great and after 45min per headlight they both looked like new.
Unfortunately after 9 months oxidation quickly started to set in.
So I hesitantly took the advice from the kid at the auto parts store to use the CV Headlight Restore kit Headlight Restoration | Headlight Cleaner in the silver bag. I was skeptical but thought it was worth a shot and still cheaper than new headlights.
WOW... I was really impressed! Where the CV kit differs from all the other kits on the market is that you apply a sealer to fill in all the tiny pits and scratches in the lens. The sealer REALLY made the headlights look like new and hardens so they are impervious to future pitting and scratches.
Just this past week we sold this vehicle and got a 4Runner !!!
So over 12 months after I used the CV kit on the headlights they still looked like new. For the money and the time you will spend, which was much less with the CV kit, it is the only way to go in my mind.