If you're serious about keeping your engine running smoothly, Hot Shot's Secret LX4 Lubricity Extreme is a game-changer. I've been using this in my diesel truck for months, and the difference is noticeable from the first tank.

The biggest win? It actually works. My 2015 Silverado with 150k miles used to have rough cold starts - now it purrs like a kitten even on freezing mornings. The fuel injector noise that had me worried? Gone after two fill-ups.

What surprised me most was the MPG boost. I gained nearly 2 mpg on highway drives. At current diesel prices, the product pays for itself quickly. The gallon jug lasts forever too - just 1oz per 10 gallons means about 128 treatments per container.

The protection aspect is where LX4 really shines. Knowing today's ultra-low sulfur diesel lacks proper lubricity, this additive gives me peace of mind against those terrifying CP4 pump failures I keep hearing about in online forums.

A few things to note: It won't turn a clunker into a showroom-fresh engine overnight, and the bottle design could be improved (some users report cap issues). But for $0.10 per gallon in protection that actually delivers results? That's a no-brainer in my book.

Pro tip: For winter use, consider their anti-gel version if you live in cold climates - learned that lesson the hard way when my regular LX4 partially froze at -15°F last January!