Schaeffer's Penetro 90 High Performance Penetrating Oil
Priced as of May 21, 2026
4.7(270 ratings)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 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.
- H340 “May cause genetic defects.”
GHS Category 1 germ-cell mutagenicity — classified as suspected of causing heritable genetic damage.
- H350 “May cause cancer.”
GHS Category 1 carcinogenicity — classified as suspected of causing cancer with repeated or prolonged exposure.
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. 2024-09-09)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 H319SkinSituationalMfr. SDS §8 · 29 CFR 1910.138(a) · GHS H315LungsRecommendedMfr. SDS §8 · 29 CFR 1910.1000 · GHS H340Ventilation—No PPE in published sourcesShow details for all categories ▾Hide details ▴
From the manufacturer’s Safety Data Sheet, Section 8
“SDS §2 classifies Eye Irritation Category 2A (H319) at the mixture level — aerosol mist is the primary exposure pathway.”
— Schaeffer's
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
“SDS §2 classifies Skin Irritation Category 2 (H315) at the mixture level — brief handling during aerosol application is the typical exposure; prolonged or repeated contact is the relevant trigger.”
— Schaeffer's
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
“SDS §2 classifies Acute Toxicity (Inhalation) Category 4 (H332 — harmful if inhaled) at the mixture level — aerosol application creates fine mist and H332 is the escalation driver. H332 maps to recommended, not required; H331 (toxic if inhaled, Cat 3) is absent from §2.”
— Schaeffer's
U.S. regulatory standard
29 CFR 1910.1000; 1910.1200
“Each employer shall assure that no employee is exposed to an inhalation concentration of any substance shown in Tables Z-1, Z-2, or Z-3 in excess of the limits in the tables.”
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.
The Podium · Top 3 in Penetrating Oil / Multi-Purpose Lubricant
See the full ranking →This product ranks #10 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 GHS carcinogen and mutagen classifications and a Prop 65 warning for cancer and reproductive toxicity — the health profile warrants serious consideration before regular use. Penetration performance is strong: Amazon verified-purchase reviewers (4.7 stars, 270 reviews) confirm reliable results on stuck automotive fasteners, and the non-evaporating oil base delivers lasting re-seizure protection that solvent-only competitors cannot match. Aerosol mist in enclosed spaces is the primary inhalation risk. Penetro 90 is specifically formulated to free seized and rusted fasteners — not a silicone spray, white lithium grease, or general-purpose lubricant for moving parts.
What it is and how it performs
Penetro 90 is an oil-based penetrating fluid that wicks into rusted and seized fasteners to break the corrosion bond so the hardware can turn. Apply with the aerosol straw, allow at least 5–15 minutes of dwell on light-to-moderate rust, and then work the fastener with a wrench or breaker bar. On heavy rust, Amazon verified-purchase reviewers (4.7 stars, 270 reviews) describe multiple applications over longer dwell periods as the typical pattern — the oil-based carrier rewards patience rather than quick solvent evaporation.
The non-evaporating oil base is the defining characteristic: after penetration, the lubricant film stays on the fastener, providing re-seizure protection and ongoing corrosion inhibition. Three named corrosion inhibitor systems and a disclosed extreme-pressure additive in the formula make this a more durable protective coating than products that rely on a single petroleum carrier.
Who should buy this — and who should skip it
A strong choice for the hobbyist restorer or home mechanic who needs reliable penetration performance and genuine long-term bolt protection — the oil base and multi-inhibitor package suit staged teardown work where fasteners will be revisited. Anyone who applies penetrating oil regularly or works in enclosed spaces should weigh the DANGER aerosol classification and Prop 65 warning carefully.
Safety and environmental impact
DANGER signal word driven by GHS carcinogen (Category 1A), mutagen (Category 1B), and STOT repeated-exposure classifications at mixture level, plus an aspiration hazard — do not induce vomiting if ingested, seek medical attention. Aerosol application is the primary inhalation pathway (classified harmful if inhaled at mixture level). A Prop 65 warning for cancer and reproductive toxicity is confirmed on the back of the can; PFAS classification applies due to PTFE content confirmed via TSCA regulatory listing.
Environmental: petroleum carrier with ingredient-level aquatic toxicity. PFAS hard cap applies. Not CARB-compliant for consumer use per back-label notation.
Frequently asked questions
Is Schaeffer's Penetro 90 High Performance Penetrating Oil safe to use?▾
The Safety Data Sheet for Schaeffer's Penetro 90 High Performance Penetrating Oil carries a DANGER signal word, with classified hazards including H222 (extremely flammable aerosol); H304 (may be fatal if swallowed and enters airways); H315 (causes skin irritation). 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 Schaeffer's Penetro 90 High Performance Penetrating Oil score on CarCareTruth?▾
CarCareTruth scores Schaeffer's Penetro 90 High Performance Penetrating Oil at 5.6 out of 10 on the composite CCT score, with a health sub-score of 1.2/10. 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 Schaeffer's Penetro 90 High Performance Penetrating Oil?▾
Per the Safety Data Sheet ingredient disclosure: SDS §3 (rev. 2024-09-09): Distillates (petroleum), hydrotreated heavy naphthenic (CAS 64742-52-5) ≥25–<50%; Distillates (petroleum), hydrotreated light naphthenic (CAS 64742-53-6) ≥25–<50%; Solvent naphtha (petroleum), medium aliphatic (CAS 64742-88-7) ≥5–<10%; Isobutane (CAS 75-28-5) ≥5–<10%; Antimony dialkyl dithiocarbamate (CAS 15890-25-2) ≥1–<3%. PTFE present per §15 TSCA (below §3 reporting threshold).
From the manufacturer
Marketing copy from Schaeffer's, via Amazon. Not editorial.
- •Prevents thread stripping to release stuck bolts: Busts through rust that has become packed into the threads of the bolts to lubricate and allow the rust particles to easily slide over each other so bolts loosen and release.
- •Triple protection against rust and corrosion protection: Contains three rust and corrosion inhibitors that help block moisture and protect metal surfaces from rust and corrosion.
- •One product, many uses: Excellent to use on heim joints, wheel studs and weight jack bolts. Ideal for valves, taps and dies, hinges, linkages, cutting tools, locks, conveyors, air power tools, control cables, rollers and hoist chains.
- •Triples time between applications: Penetro 90 is an oil-based penetrating oil, which gives it better lubricating properties and means it doesn’t evaporate quickly or require frequent applications.
- •Long-lasting lubricant film: Made with proprietary friction releasing and extreme pressure additives to deliver highly reliable protection against friction and wear to increase component life.
Weekly pick
One product, one safety verdict, every week. No spam.
Manufacturer videos
Manufacturer images
Manufacturer specifications
- Material
- Oil
- Brand
- Schaeffer Manufacturing Co
- Package Information
- Can
- Liquid Volume
- 13 Fluid Ounces
- Item Weight
- 467 Grams
- Brand Name
- Schaeffer Manufacturing Co
- Item Form
- Spray
- Global Trade Identification Number
- 00744954000029
- Manufacturer
- Schaeffer Manufacturing Co.
- Unit Count
- 1.0 Count
- UPC
- 744954000029
- Number of Items
- 1
More in Penetrating Oil / Multi-Purpose Lubricant
Fluid Film
NAS Aerosol Penetrant & Lubricant
CCT 7.5 · RecommendedHealth 9.0
Kroil
Penetrant Original Aerosol
CCT 6.9 · DecentHealth 4.9
Boeshield
T-9 Rust & Corrosion Protection
CCT 6.5 · DecentHealth 4.7
WD-40
Specialist Rust Release Penetrant Spray
CCT 6.4 · DecentHealth 7.5
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.