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.
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.
This product ranks #7 of 16 in Fuel Injector Cleaner.Three above it ↓
Last reviewed July 5, 2026
TL;DR PEA formula confirmed from Royal Purple's brand TDS, with an explicit GDI positioning few competitors name directly. Health score 5.0: DANGER from H304 aspiration hazard and a Prop 65 warning on the product listing. Do not induce vomiting if ingested; seek medical attention.
Max-Clean uses PEA chemistry confirmed by the brand's TDS, dosed one bottle per tank. PEA is the most-studied class for intake valve deposit removal and injector cleaning. Royal Purple targets GDI engines but TDS confirms compatibility with port injection, carbureted, 2-cycle, and 4-cycle engines on gasoline and diesel. Community signal: well-reviewed by owners on Amazon, though with less depth than the category benchmark. No independent SAE paper or dyno test found; the brand cites a sponsored track test only.
Best for GDI owners running non-Top Tier gasoline who want a PEA-class treatment or mild deposit cleanup. Skip it with consistent Top Tier use; the OEM detergent package covers this. Skip it for severe rough idle or stalling; a single consumer bottle is not enough, and professional ultrasonic cleaning is the right call.
SDS §2 is DANGER from H304 only (aspiration toxicant: swallowed liquid entering the lungs, not contact or inhalation). No skin, eye, or respiratory H-codes at mixture level. Do not induce vomiting if ingested; seek medical attention. The product listing carries a Prop 65 warning; SDS §15 names cumene as the carcinogen. The product enters the fuel tank and combusts; exhaust byproducts are the environmental endpoint.
Yes. Royal Purple's TDS explicitly positions Max-Clean for GDI engines, where intake valve deposit buildup is a known problem because fuel no longer washes the backs of the valves. The product is also compatible with port-injection, carbureted, 2-cycle, and 4-cycle engines, and with both gasoline and diesel. GDI-specific positioning is one of the clearest compatibility claims in the fuel injector cleaner category.
Max-Clean uses PEA (polyetheramine), confirmed by Royal Purple's official TDS. PEA is the most independently studied detergent class for injector and intake valve deposit removal. No independent SAE technical paper specific to this product has been located, but PEA chemistry as a class has documented deposit-removal efficacy in the SAE literature. Community sentiment is consistently positive with a solid review pool on Amazon, though less community depth exists than for category leaders like Techron.
The DANGER signal word on the SDS comes from a single H-code: H304, the aspiration hazard. H304 means that if the liquid is swallowed and enters the lungs, it can cause serious damage. It is not a skin, eye, or inhalation hazard at the mixture level. SDS §2 has no H315 (skin irritation), H319 (eye irritation), or H335 (respiratory irritation). The product also carries a Prop 65 warning for cumene (a trace carcinogen named in SDS §15). Do not induce vomiting if ingested; seek medical attention.
Royal Purple's TDS describes Max-Clean as both a one-time flush for existing deposit symptoms and a periodic maintenance treatment. The standard dose is one 20 oz bottle per nearly empty tank, treating up to 20 gallons. For ongoing maintenance, Royal Purple does not specify a set interval on the TDS; common community practice for PEA-class treatments is every 5,000-10,000 miles or when a rough idle or MPG drop is noticed. Running Top Tier gasoline already provides a detergent package that reduces the need for supplemental treatment.
Marketing copy from Royal Purple, via Amazon. Not editorial.
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