CRC Screwloose Super Penetrant
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Prices may varySerious hazard — read before use
The manufacturer's Safety Data Sheet classifies this product with one or more GHS Category 1 health hazards — the most severe tier. The hazard statements in quotes below are the verbatim GHS language from the SDS, as required by OSHA's Hazard Communication Standard. The line under each statement translates the GHS classification into plain language.
- H304 “May be fatal if swallowed and enters airways.”
GHS Category 1 aspiration toxicity — thin, oily liquids can slip into the lungs if swallowed, causing chemical pneumonia.
If swallowed, inhaled, or splashed in eyes:
Call Poison Control immediately at 1-800-222-1222 (US, 24/7, free) and have the product container with you. Poison Control's standing guidance is to not induce vomiting after chemical exposure; they will direct first-aid steps based on the specific product.
About this product's hazards. This product's Safety Data Sheet uses signal word danger. Read the manufacturer's SDS and follow all safety instructions before use. CarCareTruth ratings translate the manufacturer's safety sheet. They do not replace the SDS or substitute for a hazard assessment specific to your task.
Health score is for adult use as intended, per the manufacturer's SDS. It does not model child ingestion, accidental spill cleanup, or off-label use. See the safety panel below for full hazard classification, and /disclaimer for the full editorial scope.
From the Safety Data Sheet
Full SDS ↗ (rev. 2024-11-19)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.
EyesSituationalMfr. SDS §8Skin—No PPE in published sourcesLungsSituationalMfr. 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
“No H319 or H318 in SDS §2 mixture classification. Aerosol form factor is the exposure trigger — fine mist near face during spray application.”
— CRC
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 skin. Absence does not imply “not needed” — consult the full Safety Data Sheet.
From the manufacturer’s Safety Data Sheet, Section 8
“H335 is absent from SDS §2 mixture classification. H336 (narcotic effects, STOT SE Cat 3) is present in §2 but H336 is CNS narcosis — not a respiratory irritant — and does not escalate lungs PPE above the aerosol baseline. Aerosol mist in enclosed spaces is the inhalation exposure trigger.”
— CRC
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.
The published Safety Data Sheet for this product does not specify ventilation protection for consumer use.
Workplace context
29 CFR 1910.134(a); 1910.1000
“the primary objective shall be to prevent atmospheric contamination [via] accepted engineering control measures (for example, enclosure or confinement of the operation, general and local ventilation…).”
Triggered by GHS H336 on the SDS.
OSHA standards apply to workplaces. Cited here as the U.S. reference threshold for the underlying hazard class.
PPE tiers translate the manufacturer’s SDS and U.S. regulatory standards. Not professional safety advice. How we report safety.
The Podium · Top 3 in Penetrating Oil / Multi-Purpose Lubricant
See the full ranking →This product ranks #11 of 11 in Penetrating Oil / Multi-Purpose Lubricant.Three above it ↓
CarCareTruth's Analysis
Last reviewed May 26, 2026
TL;DR DANGER-rated aerosol with a Prop 65 warning for cancer and reproductive toxicity — aspiration hazard if swallowed; do not induce vomiting. Works on moderate rust in 2–4 minutes; heavier corrosion may require an overnight soak. Aerosol mist in enclosed spaces is the primary inhalation concern.
What it is and how it performs
CRC Screwloose wicks a thin formula into corroded threads to break rust's grip on seized fasteners. Amazon verified-purchase reviewers (4.6 stars across 816 reviews) confirm consistent results on light-to-moderate rust — 2–4 minutes dwell on moderate corrosion; heavily rusted hardware may need a longer soak. The aerosol straw reaches tight clearances and blind bores. Paraffinic oil fractions leave a light residual film, but no dedicated corrosion inhibitor package is disclosed — re-seizure protection is modest.
Who should buy this — and who should skip it
A practical choice for homeowners or occasional mechanics dealing with a stuck fastener, particularly where plastic components are involved (formula is marketed as plastic-safe). Skip it for regular enclosed-space use — DANGER classification and a confirmed Prop 65 warning compound with repeated aerosol exposure.
Safety and environmental impact
DANGER is driven by an aspiration hazard if swallowed — do not induce vomiting if ingested; seek medical attention. Prop 65 warning for cancer and reproductive toxicity confirmed in SDS §15 and on the product label (Rainforest API false negative; overridden from SDS and label). No H335 in mixture classification; aerosol mist in enclosed spaces is the inhalation trigger.
Environmental: petroleum-distillate carrier, two bioaccumulative ingredients, H411 at mixture level, EPA-basis VOC ~797 g/L. CARB-compliant for all 50 states per SDS §15.
Frequently asked questions
Is CRC Screwloose Super Penetrant safe to use?▾
The Safety Data Sheet for CRC Screwloose Super Penetrant carries a DANGER signal word, with classified hazards including H222 (extremely flammable aerosol); H336 (may cause drowsiness or dizziness); H304 (may be fatal if swallowed and enters airways). The Amazon listing also carries a California Prop 65 warning. See the PPE breakdown above for use-case-specific guidance translated from the SDS hazard codes.
How does CRC Screwloose Super Penetrant score on CarCareTruth?▾
CarCareTruth scores CRC Screwloose Super Penetrant at 5.5 out of 10 on the composite CCT score, with a health sub-score of 5.0/10. The CCT score blends real-world effectiveness, ingredient health impact pulled from the manufacturer's safety sheet, and environmental footprint against a published category rubric. See the methodology link on this page for the full scoring breakdown.
What's in CRC Screwloose Super Penetrant?▾
Per the Safety Data Sheet ingredient disclosure: SDS §3 (rev. 2024-11-19): Distillates (petroleum), hydrotreated light (CAS 64742-47-8) 60–80%; Naphtha (petroleum), hydrotreated heavy (CAS 64742-48-9) 5–10%; 2-Propanol, 1-(1-methyl-2-propoxyethoxy)- (CAS 29911-27-1) 3–7%; Carbon dioxide (CAS 124-38-9) 1–5%; Distillates (petroleum), solvent-dewaxed heavy paraffinic (CAS 64742-65-0) 1–5%; Paraffin oils (petroleum), catalytic dewaxed light (CAS 64742-71-8) 1–5%; Nonane (CAS 111-84-2) 0.1–1.5%; Trade secret…
From the manufacturer
Marketing copy from CRC, via Amazon. Not editorial.
- •CRC INDUSTRIES: A market leader that offers impeccably designed chemical solutions to maintain, protect and repair different marine, heavy-duty motor vehicles, industrial-grade engines, household tools, and electrical equipment
- •PENETRATING SOLVENT: Our penetrant is a super-fast, powerful, and concentrated solvent for attacking corrosion to free corroded fasteners and other seized mechanical components.
- •QUALITY FORMULA: This penetrating oil works effectively and instantly, even in minute and tightly fitted crevices. It has a petroleum distillate base and is safe to use on all plastics.
- •APPLICATIONS: The penetrating solution is ideal for nuts and bolts, pins, screws, bushings, clips, hinges, snaps, lugs, caps, locks, washers, and sliding mechanisms.
- •PRODUCT SPECIFICATIONS: Screwloose Super Penetrant is available in an 11 wt oz. aerosol can.
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Manufacturer specifications
- Material
- Plastic
- Brand
- CRC
- Package Information
- Can
- Liquid Volume
- 470 Milliliters
- Item Weight
- 0.01 Ounces
- Brand Name
- CRC
- Recommended Uses For Product
- Mechanical,Electrical
- Specific Uses For Product
- Lubrication and Corrosion Prevention in Mechanical Assemblies and Plastic Components
- Item Form
- Aerosol
- Global Trade Identification Number
- 00078254030609
- Manufacturer
- CRC Industries
- Unit Count
- 11.0 Ounce
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