[Alex V.]

I'm not going to say break-in oils will hurt an engine long term, or at least not one that's just used casually. However, I do not think they're necessary and probably not nearly as economical as oils formulated for normal duty. The last cam break-in I did was on my Suburban's 350. Albeit it was a standard, calm truck grind, but I used Valvoline conventional oil with a bottle of Lucas high zinc break-in additive. After 1,000 miles I changed it out, back to Valvoline MaxLife 10w30 (no additive) and it's gone several thousand since with no trouble. About 8 years ago when I caught wind of the ZDDP talk I was chatting with the local preferred engine rebuilder, who has generous experience with all types of engines including race applications, and he said a half bottle of the common ZDDP additives is plenty. Since then I've only used a whole bottle when breaking in an engine or component, otherwise I use 1/2 bottle or none at all with no repercussions. However, oil is one of those things that you won't have peace about unless you use what you think will do the job.

FWIW, after quite a bit of back and forth in my '85 C3500 (stock 454) with Valvoline VR1 racing oil (20w50), conventional 10w30 with and without STP oil stabilizer (supposedly has extra ZDDP), and a long stint with Schaeffer's synthetic blend 15w40, I settled on Schaeffer's syn blend 10w30. I run Valvoline Maxlife 10w30 in my Suburban's 350 (it saw dad's '97 Suburban past 400,000 so I have no doubts) and full syn 5w30 in my '13 Cruze - Valvoline up to 50,000 mi. then switched to Schaeffer's and am currently at 70,500. Synthetics are where it's at nowadays.