Brand · Kano Laboratories

Which Kroil should you buy?

The one machinists whisper about. There are two of them.

Kano Laboratories makes the penetrant other penetrants get measured against. We rate both of its cans "Maximum" for penetration depth, the only brand in our catalog with two cans at the top of the scale, and Kroil Original holds the highest score of any penetrant we cover.

The catch is the price tier: both are pro-priced, and our own head-to-head says PB B'laster gets you most of the way for about half the money. So the real question is not whether Kroil works. It is whether your job is the kind that needs it, and if so, whether you want it with silicone or without.

Pick by job

Which Kroil for which job

A seized bolt every other can has already failed on
Kroil
Rated Maximum penetration and the top-scoring penetrant we cover. This is the impossible-job can.
Penetrating Oils · Maximum · 13 oz · our score 98%
Check Price Review
Firearms, reels and delicate mechanisms
Sili Kroil
Same Maximum penetration plus silicone, so the part is left lubricated once it frees up.
Penetrating Oils · Maximum · 13 oz · our score 97%
Check Price Review

Check Price links go to Amazon. We may earn a commission at no extra cost to you. Disclosure.

Side by side

The Kroil lineup, specced

Product	Type	Penetration	Size	Price	Best for	Our score
Kroil	Penetrating Oils	Maximum	13 oz	$$$	precision machinery, firearms	98%
Sili Kroil	Penetrating Oils	Maximum	13 oz	$$$	precision instruments, firearms	97%

Head-to-Head

How Kroil does in a fight

WD-40 vs Kroil

Kroil wins on pure penetrating power. WD-40 wins on price and versatility.

Read the head-to-head →

PB B'laster vs Kroil

Kroil penetrates deeper; PB B'laster offers 90% of the performance at half the price.

Read the head-to-head →

Rankings

Where Kroil places in our best-of lists

#1Kroilof 8 in Best Penetrating Oil

Put it to work

Jobs we reach for Kroil on

Seized-part jobs where a Kroil can is one of our picks, and why.

How to Remove a Seized Brake Caliper Bolt

Kroil: The pick for an overnight soak when the bolt is badly crusted.

Moderate · soak 30 min to overnight · heat with care

How to Loosen a Stuck Brake Bleeder Screw

First pick

Kroil: Made to creep into very tight clearances, which is the whole problem with a bleeder thread.

Moderate · soak several hours to overnight · no heat

How to Remove a Rusted Exhaust Manifold Stud or Nut

First pick

Kroil: Built to creep into very tight clearances. Exhaust threads need several days of it.

Hard · soak 1–3 days, reapplied · heat ok

How to Remove a Stuck Spark Plug from an Aluminum Head

First pick

Kroil: Fine, creeping penetrant for tight steel-in-aluminum threads.

Hard · soak 15 min to overnight · no heat

How to Remove a Stuck Bike Seatpost

First pick

Kroil: Creeps into very tight clearances, and a seatpost fit is about as tight as it gets.

Hard · soak 1–3 days, reapplied · no heat

How to Remove a Stuck Bottom Bracket

First pick

Kroil: The fine-clearance creeper. Fine threads and a long engagement suit it.

Hard · soak overnight · no heat

How to Free a Seized Bench Vise

Kroil: For the overnight soak on the screw threads.

Moderate · soak overnight · heat with care

Asked and answered

Kroil questions

What is the difference between Kroil and Sili Kroil?

Sili Kroil is Kroil's penetrant with silicone added. Both rate Maximum for penetration in our reviews. Pick Original for freeing rusted, seized metal; pick Sili Kroil when the part is a precision instrument, firearm or reel and you want a slick film left behind.

Is Kroil better than PB B'laster?

On penetration, yes: our head-to-head gives Kroil the edge on deeper micro-penetration and staying active longer. PB B'laster wins on price and availability, and most people will be fine with it for daily use. Save Kroil for the jobs PB could not finish.

Is Kroil worth it over WD-40?

For a genuinely seized fastener, yes. Our WD-40 vs Kroil verdict: Kroil wins on pure penetrating power, WD-40 wins on price and versatility. WD-40 Original is a moisture displacer first; Kroil is a dedicated penetrant.

Where can I buy Kroil?

Our Kroil review notes it can be hard to find in local stores and often needs ordering online. Both Kano cans on this page link to their Amazon listings.

Playing the field