#1 in Penetrating Oil
2 days running
Priced as of May 13, 2026
4.7(7,732 ratings)Subscribe & Save: $23.74 (5% off)Buy on AmazonSaved to your guest loadout. Sign up to also save to your Cabinet (consumables) or Kit (tools you own).
As an Amazon Associate and affiliate partner, CarCareTruth earns from qualifying purchases. Full disclosure
Prices may varyFrom the Safety Data Sheet
Full SDS ↗ (rev. 2025-10-06)GHS hazard codes are quoted from the manufacturer’s Safety Data Sheet. PPE tiers below translate those codes and the listed ingredient chemistry; they are not CarCareTruth recommendations.
EyesRecommendedMfr. SDS §8 · 29 CFR 1910.133(a)(1) · GHS H319SkinRecommendedMfr. SDS §8 · 29 CFR 1910.138(a) · GHS H315LungsSituationalMfr. SDS §8 · 29 CFR 1910.1200(f) · GHS H304Ventilation—No PPE in published sourcesShow details for all categories ▾Hide details ▴
From the manufacturer’s Safety Data Sheet, Section 8
“H319 (eye irritation Cat 2A) present in SDS §2 mixture classification — aerosol mist is the primary exposure pathway.”
— Kroil
U.S. regulatory standard
29 CFR 1910.133(a)(1)
“The employer shall ensure that each affected employee uses appropriate eye or face protection when exposed to eye or face hazards from… liquid chemicals…”
ANSI Z87.1 (incorporated via §1910.6)
OSHA standards apply to workplaces. Cited here as the U.S. reference threshold for the underlying hazard class.
CarCareTruth publishes the cited sources verbatim and does not advise what action a user should take. Consult the full SDS before use.
From the manufacturer’s Safety Data Sheet, Section 8
“H317 (skin sensitization Cat 1) present in SDS §2 mixture classification — the carrier can cause sensitization with repeated contact.”
— Kroil
U.S. regulatory standard
29 CFR 1910.138(a)
“appropriate hand protection when employees' hands are exposed to hazards such as those from… chemicals which produce an adverse effect on the skin or eyes…”
OSHA standards apply to workplaces. Cited here as the U.S. reference threshold for the underlying hazard class.
CarCareTruth publishes the cited sources verbatim and does not advise what action a user should take. Consult the full SDS before use.
From the manufacturer’s Safety Data Sheet, Section 8
“No H335 (respiratory irritation) in SDS §2. Aerosol form factor creates fine mist inhalation risk; enclosed-space application is the specific trigger.”
— Kroil
U.S. regulatory standard
29 CFR 1910.1200(f); 1910.132(d)
“The employer shall assess the workplace to determine if hazards are present, or are likely to be present, which necessitate the use of personal protective equipment.”
OSHA standards apply to workplaces. Cited here as the U.S. reference threshold for the underlying hazard class.
CarCareTruth publishes the cited sources verbatim and does not advise what action a user should take. Consult the full SDS before use.
No PPE specified in published sources for ventilation. Absence does not imply “not needed” — consult the full Safety Data Sheet.
PPE tiers translate the manufacturer’s SDS and U.S. regulatory standards. Not professional safety advice. How we report safety.
CarCareTruth's Analysis
Last reviewed May 15, 2026
TL;DR DANGER-rated aerosol — skin sensitization and eye irritation at the mixture level, aspiration hazard if swallowed. Penetration is among the best documented in the category: community-confirmed on heavy rust in 5–15 minutes with a single application.
What it is and how it performs
Kroil Penetrant Original (formerly AeroKroil) wicks into corroded threads and breaks rust's grip so a seized fastener can turn. Light-to-moderate rust yields in about 10 minutes. For heavy, long-seized rust, community data confirms results in 5–15 minutes — near the top of the category on penetration speed. The residue provides above-average short-term re-seizure protection confirmed in multi-week follow-ups.
Who should buy this — and who should skip it
Strong first choice for a difficult seized fastener. For frequent enclosed-space use, the DANGER classification (skin sensitization, aspiration hazard) and aerosol mist exposure documented in SDS §2 are the relevant risk considerations.
Safety and environmental impact
DANGER rating at §2 mixture level: aspiration hazard if swallowed, skin sensitization, skin irritation, eye irritation. Do not induce vomiting if ingested — seek medical attention. Aerosol mist is the primary eye-exposure pathway; repeated carrier contact is a skin sensitization risk. No H335 in §2 — aerosol mist in enclosed spaces is the inhalation concern. The Prop 65 warning on some Amazon listings is a confirmed false positive per SDS §15.
VOC estimated 151–350 g/L; 50-State VOC Compliant. CARB-compliant rating reflects exempt-compound accounting used in California's VOC calculation — the LVP (low-vapor-pressure) aliphatic hydrocarbon fraction may qualify as CARB-exempt, allowing the product to meet state VOC limits while the absolute petroleum-distillate solvent content remains substantial; ventilation requirements apply regardless of the CARB status on the label. Petroleum-distillate carrier is not biodegradable; one ingredient is aquatically toxic at ingredient level (SDS §12).
From the manufacturer
Marketing copy from Kroil, via Amazon. Not editorial.
- •Trusted by Professionals: Kroil Original Penetrant is a rust penetrating aerosol spray that tackles stuck bolts and frozen metal parts with ease
- •Unmatched Penetrating Power: This oil easily penetrates small openings and tight threads and crevices, making it the ideal rust remover for tough repair jobs and stuck parts
- •Multi-Use Versatility: Kroil Original Penetrant is trusted for any job with moving parts; use for bike maintenance, chain lubrication, rusted hinges, garage door rollers, or seized bolts
- •Industrial-Strength Lubricant: Kroil penetrates and removes rust, inhibits corrosion, cleans carbon deposits, and displaces moisture; withstands any condition, including high humidity and salt water
- •About Kroil: Kroil solves universal challenges by producing the very best penetrants on the market to help hard-working folks
Weekly pick
One product, one safety verdict, every week. No spam.
Manufacturer videos
Manufacturer images
Manufacturer specifications
- Material
- Metal
- Brand
- KROIL
- Package Information
- Can
- Liquid Volume
- 10 Fluid Ounces
- Item Weight
- 0.84 Pounds
- Brand Name
- KROIL
- Recommended Uses For Product
- Mechanical
- Specific Uses For Product
- Mechanical
- Item Form
- Aerosol,Oil
- Global Trade Identification Number
- 00857236004018
- Manufacturer
- Kano Laboratories LLC
- Unit Count
- 10 Ounce
More in Penetrating Oil
Liquid Wrench
Penetrating Oil
CCT 5.8 · DecentHealth 4.4
PB Blaster
Penetrating Catalyst
CCT 5.7 · DecentHealth 3.7
As an Amazon Associate and affiliate partner, CarCareTruth earns from qualifying purchases. Full disclosure
Community
0 postsShare how you use this product
Drop a quick comment or post a full review with photos and a star rating.
Sign in to postNew here? Create a free account.
Top Amazon review
↗External — Amazon's most-helpful review for context.
Better than peanut butter
I first started using this stuff in the Air Force. In my opinion it saturates seized but and bolt threads better than most every other penetrant. I spray every nut and bolt before I ever put a wrench on it. Let it sit and watch it get drawn in the threads. I’ve not broken a bolt in years and I work on some really old stuff now. Easy to use, a little bit goes a long way.