In my experience, AHA (alpha hydroxy acid) products or rosehip oil have helped to lighten my ace scars over several months. I've used Alpha Hydrox, MD Forte, and Alpha Glycolix products (not at the same time) with good results.
The rosehip oil I'm currently using is Pai brand and I like it so far.
Type: 3b/3c (i), below shoulder length. Modified CG since 5/2004; growing gray since 5/2007.
CO wash: A-O GPB LYY, Salon Care Honey Almond, Devacurl OC, rotating others
Leave-ins: BWC, KCKT, coconut oil overnight
Styling: BRHG, MGA Sculpting Gel, Aubrey Organics Mandarin Magic Gel, LOTD AVG, LALSG
DT: Terax Crema, Moroccan Oil Restorative Mask, Je Veux Revitalizing Mud Mask, Kiehl's Olive Fruit Oil Deeply Repairative Hair Pak, Curl Junkie Deep Fix