WD-40 OriginalvsKroil
WD-40 Original
The original. Goes in easy. Loosens everything.
Where It Wins
- +Much cheaper
- +Available everywhere
- +Multi-purpose
- +Smart Straw convenience
Kroil
The legend. One-millionth of an inch. Nothing is too tight for Kroil.
Where It Wins
- +Superior penetration
- +Creeps into microscopic gaps
- +Preferred by machinists
- +Aerospace pedigree
Spec Comparison
| Spec | WD-40 Original | Kroil |
|---|---|---|
| Satisfaction | 97% | 98% |
| Penetration Depth | Medium | Maximum |
| Price Tier | budget | pro |
| Volume | 12 oz | 13 oz |
| Best For | rusty bolts, squeaky hinges, stuck mechanisms | precision machinery, firearms, aerospace |
Kroil wins on pure penetrating power. WD-40 wins on price and versatility.
This isn't really a fair fight. WD-40 is a multi-purpose product that happens to penetrate. Kroil is engineered from the ground up for maximum penetration, creeping into one-millionth-of-an-inch gaps. Kroil costs more, but when you have a truly stuck part, the price difference is irrelevant.
Affiliate disclosure: Links go to Amazon; we earn a small commission at no extra cost to you.
Dig Deeper
How to Free a Seized Bolt
Step-by-step guide to freeing seized, rusted, or frozen bolts using penetrating oil. The right technique makes all the difference.
🚪GuideHow to Lubricate Squeaky Door Hinges
A hinge that announces every entrance has one problem and one fix. What to spray, where to spray it, and why wiping the excess matters more than the spray itself.
PicksBest-OfBest Penetrating Oil
Our top picks for penetrating oils in 2026. We tested WD-40, PB Blaster, Kroil, and more to find the ones that go deepest.
PicksBest-OfBest Multi-Purpose Lubricant
The best do-everything lubricants for home, shop, and field. When you want one bottle that handles anything you throw at it.