Hi there
I have personally had great success with myrrh and frankincense essential oil with scar tissue. It depends on the size of the scar. Mine were on my face from acne. I used both these oils neat (I only use therapeutic grade essential oil on my face or anywhere for that matter).
I did follow a skin regimen every day (and still do) which I have written about here It took about 3 months before I noticed any difference and then it was about a year later that I remember looking at my skin and thinking how smooth and soft it was!!
It is no surprise to me that the essential oils recommended for wrinkles also seem to work on scars. I have see that helichrysum can also be used, but if you are using the right essential oil, it is hard to get at the right quality. My company didn't have the oil for 1 1/2 years because they didn't want inferior oil. It is also an expensive oil as using it every day you would go through a lot.
I would prefer to use the more resin type essential oils as I have had so much success with them.
I hope this helps
Jen