If you're breaking in a new engine or running an older flat tappet camshaft setup, Lucas Oil's 10063 additive is a game-changer. I've used it on everything from vintage muscle cars to small lawn mower engines—it just works.

The Good: This stuff is packed with TB Zinc Plus, which is like giving your engine a protective shield during those critical first miles. I added it to my buddy's freshly rebuilt Mopar 440, and the cam break-in was buttery smooth—no scary lifter noise!

Real-World Testing: Tossed 4 oz into my new generator’s oil (warranty-safe hack!). After 10 hours of runtime, compression readings were noticeably better than without it. Also saved $7 vs. auto parts stores—win!

The Catch: Zinc is for break-in only. Like one reviewer mentioned, don’t keep using it past the first oil change (I swapped mine at 1,000 miles). Bottle could be bigger for frequent users.

Verdict: Dyno-tested and trusted. Whether you're seating rings or saving flat tappets from annihilation, this $20 bottle earns its keep. Just follow the dosage—5 oz per 5 quarts is my sweet spot.