Not sure whats in Tru-Oil but I've never had a problem with scratches, I do think some people put it on way to thick though almost painting the gun with it, I normally just put some on a rag and rub into the wood, The sheen conditioner (or for a glossy finish wax) provide's a protective coat, I have used this method for both hunting and target rifles without any issues and very good results, Warming the wood "gently" does help as it opens the grain allowing the oil to penetrate, What is however important is removing the old finish before attempting to apply anything, this is normally do with wire wool and denatured alcohol, the more time spent prepping the better and more durable the finish will be.