CarCareTruth Score
Decent, but it's tough on the environment.
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Prices may varyThe 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.
GHS Category 1 aspiration toxicity — thin, oily liquids can slip into the lungs if swallowed, causing chemical pneumonia.
GHS Category 1 eye damage — classified as causing irreversible eye damage on contact.
If swallowed or splashed in eyes:
The aspiration hazard (H304) is about the liquid being swallowed and reaching the airway, not about breathing fumes during normal use.
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.
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.
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Translated from the manufacturer’s Safety Data Sheet, Section 2
SDS §2 classifies H318 (causes serious eye damage, Cat 1) at mixture level. The concentrate is poured into a narrow fuel-tank fill neck where drip-back is realistic, so eye protection is warranted for the pour.
U.S. regulatory standard
29 CFR 1910.133(a)(1); 1910.151(c)
“The employer shall ensure that each affected employee uses appropriate eye or face protection when exposed to eye or face hazards from… liquid chemicals, acids or caustic liquids…”
ANSI Z87.1 (chemical splash protection — 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.
Translated from the manufacturer’s Safety Data Sheet, Section 2
SDS §2 classifies H315 (skin irritation) and H317 (may cause an allergic skin reaction). The skin sensitizer classification means repeated or careless contact can provoke an allergic response, so gloves are warranted rather than merely situational.
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.
Only when: in enclosed space
Beyond SDS: translated from the ingredient chemistry
No respiratory-irritation H-code (H335) appears in SDS §2 at mixture level (H335 is ingredient-level only for one co-active). The carrier is volatile (flash point 76.67°C), so an outdoor pour concentrates little vapor, but an enclosed garage warrants a break in airflow.
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.
Scope of these PPE tiers. The tiers on this page translate the product's Safety Data Sheet where one is published, plus its ingredient chemistry, into a comparable rating. They describe a formulation, not a situation: a tier is not a safety determination for any specific user, task, quantity, or environment. The manufacturer's label and use instructions govern how the product is handled. Where the product is used at work, the employer's PPE program and hazard assessment under 29 CFR 1910.132 decide what protection is selected, not this page.
No warranties. CarCareTruth makes no warranties, express or implied, and expressly disclaims the implied warranties of merchantability and fitness for a particular purpose.
This product ranks #4 of 9 in Fuel System Cleaner.Three above it ↓
Last reviewed July 31, 2026
TL;DR A value-priced whole-system treatment built on a PEA detergent confirmed in the SDS, with PIBA indicated, that credibly reaches injectors and intake valves. The combustion-chamber coverage is a brand claim, not disclosed chemistry. Health 4.0/10 (Serious Hazard): a DANGER concentrate with serious-eye-damage and skin-sensitizer classifications plus a Prop 65 warning. Wear eye protection and gloves.
STP Complete Fuel System Cleaner is an inexpensive pour-in treatment positioned to clean the whole fuel system. Its confirmed active is a PEA (polyetheramine) detergent, which credibly cleans fuel injectors and intake valves; the brand also names a PIBA co-active and a temperature-resistant detergent for combustion-chamber deposits, though that combustion-chamber claim has no independent test data behind it. It is a periodic-maintenance dose, not a one-time flush: one 5.25 oz bottle treats up to 15 gallons, at every oil change or 4,000 miles.
Best for owners of port-injected, turbo, or older gasoline engines that have run non-Top-Tier fuel and want an inexpensive routine full-system pour. Skip it if you consistently run Top Tier gasoline, which already carries a detergent package that prevents these deposits. Skip it for severe rough idle, misfires, or injector failure beyond typical carbon fouling, where professional fuel-system service is the right call. Direct-injection owners should treat the intake-valve benefit as unverified.
SDS Section 2 is DANGER, driven by health H-codes: H318 (serious eye damage), H304 (aspiration hazard), H315 (skin irritation), and H317 (allergic skin reaction). Those force eye protection and gloves for the pour; the volatile carrier concentrates little vapor outdoors, but an enclosed garage warrants airflow. Do not induce vomiting if ingested; seek medical attention (H304). The product carries a Prop 65 warning and combusts in the engine, so exhaust byproducts are the environmental endpoint, not wastewater.
The brand describes a two-tier detergent system covering fuel injectors, carburetors, intake valves, cylinder heads, and combustion-chamber deposits. A PEA detergent is confirmed in the US SDS and credibly reaches injectors and intake valves; PIBA is named on the brand page and indicated as a co-active. The combustion-chamber and power-restoration claims are brand assertions with no independent test data on record.
The brand states the product is safe for any gasoline engine, including turbo, direct-injection, and hybrid. That is a compatibility claim, not proof of GDI cleaning: a tank-poured detergent reaches intake valves through the fuel path only on port-injected engines, so a true GDI engine's intake-valve carbon is not fuel-washed. Treat the GDI benefit as compatibility rather than verified cleaning.
The label directs one full 5.25 oz bottle into a full tank (treats up to 15 gallons), used at every oil change or every 4,000 miles. That is a periodic-maintenance dose rather than a one-time high-concentrate flush, so it is best suited to routine upkeep between oil changes.
No documented incompatibility with catalytic converters or fuel injection has been reported, and the brand positions it for the entire fuel system of modern gasoline engines. The brand makes no explicit catalytic-converter statement on this listing, so verify with the manufacturer before use in emissions-critical or warranty-sensitive applications.
The bottle, the product listing, and the brand product page all carry a Prop 65 cancer-and-reproductive-harm warning, even though this SDS revision's Section 15 does not name a specific listed substance. That combination is treated as an active label warning; it most likely reflects a precautionary manufacturer warning tied to a trace aromatic solvent component in the proprietary blend.
Marketing copy from STP, via Amazon. Not editorial.
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