Oil change

It's best to use an oil with over 1100 ppm of ZDDP already in it. I avoid additives for two reasons. First, is you don't know how well the additive will work with your chosen oil. The carrier oil in the additive is often of the lowest quality, which can degrade your oil. Also, you won't really know how much ZDDP you'll have. In a street driven car ou want to be between 1000 and about 1500 ppm. The second reason is no oil company will guarantee their product if you've introduced an additive to the solution.