For use after break-in I caution the use of ancient API oil category dollar store oil. As it would seem, there is a nee-jerk reaction among some to avoid SN/SM rated modern oils altogether. Yes these newer oils are down about 400ppm in the anti-wear additive ZDDP that we’d like to see but the fact of the matter there are a vast number of improved characteristics of the new oils over the old ones. Even SN is improved over SM.

For example, below is a list of some of the benefits one can expect with regard to improved performance characteristics of an SN rated oil versus ANY retired API category oil that came before it.

- Improved Seal Compatibility
- Improved Rust Protection
- Improved Fuel Economy (Which may mean reduced friction and improved power)
- Less volatile
- Improved Engine Sludge Protection
- Improved Piston Cleanliness
- Improved Oxidative Thickening Protection

So, if one prefers to mix their own anyway with the ZDDP additive of their choice, why not at least start with a motor oil formulated with superior base oils and the modern additive package; the best of both worlds as it were.

Back to engine break-in. For favorable results, use a dedicated engine break-in oil that doesn't have friction modifier additives.