HOAT yellow coolant flush:$115 to $200G05 spec, Ford / Chrysler / Mercedes, 2026
HOAT yellow (Hybrid Organic Acid Technology, often labeled G05) is the factory coolant for Ford pre-2018, Chrysler / Dodge / Jeep / Ram across most production, and Mercedes-Benz under the 325.0 specification. The hybrid chemistry combines OAT's long life with silicate protection for older cast-iron engine components.
Indy shop
$115 - $180
Full machine flush
Chain
$109 - $169
G05 yellow exchange
Dealer
$180 - $400
OEM Mopar / Motorcraft / Mercedes
Spec card
G05 / HOAT yellowWhat HOAT is
HOAT chemistry explained
HOAT stands for Hybrid Organic Acid Technology. The "hybrid" part is the key. A pure OAT formulation like Dex-Cool uses organic acids as the corrosion inhibitor and contains no silicates. A pure IAT formulation like classic green coolant uses silicates and phosphates as inhibitors with no organic acids. HOAT combines both, using OAT for long-term protection of aluminum components plus a small silicate package for fast-acting protection on cast iron and copper.
The G05 designation comes from the German automotive coolant classification system, which is widely used across the European-influenced spec writing at Ford and Chrysler. G05 specifies a low-silicate HOAT formulation that meets ASTM D3306 (general automotive coolant) plus the specific OEM additive package. The yellow dye is conventional but not mandatory; some G05-compliant products are also sold in pink or orange dyes for marketing differentiation.
The practical strength of HOAT yellow is broad compatibility. It works in older cast-iron block engines (like the Ford 4.6L modular V8, Chrysler 5.7L HEMI, Mercedes M112 V6) as well as newer aluminum-heavy designs. The compromise is service life. The silicate component degrades faster than pure OAT, so HOAT's 5-year / 100k interval is shorter than Dex-Cool's 5-year / 150k interval.
For owners of pre-2018 Ford trucks, Chrysler/Dodge/Jeep/Ram vehicles, and Mercedes models built under the 325.0 spec, HOAT yellow is the correct coolant. Substituting a different chemistry is not an upgrade; it is a downgrade because the silicate package matters for the specific engine architecture.
G05 product options
| Mopar 5-year / 100k Yellow | $22 - $30 | OEM at Chrysler dealers |
| Motorcraft VC-7-B Gold | $22 - $28 | OEM at Ford dealers |
| Mercedes A 000 989 08 25 | $28 - $40 | OEM at Mercedes dealers |
| Zerex G05 | $16 - $22 | AutoZone, Advance, NAPA |
| Prestone All Vehicles Yellow | $15 - $20 | Walmart, parts stores |
| Peak Long Life Yellow | $14 - $19 | Walmart, parts stores |
Per-gallon pricing sampled May 2026. Pre-diluted 50/50 ready-to-use. Concentrate runs $4 to $8 more per gallon and needs equal-part distilled water.
Mixing risk
What happens when HOAT meets other chemistries
HOAT + OAT (yellow + orange)
Worst-case mix. The silicates in HOAT precipitate when they encounter the OAT additive package, forming a gel-like sludge. The sludge clogs heater core passages and narrow radiator tubes. Fix is a complete machine flush with chemical cleaner, then refill with the correct G05.
HOAT + IAT (yellow + green)
Partial degradation. The IAT silicate package overwhelms the HOAT formulation and the corrosion protection drops to IAT levels (2-3 year interval). Not catastrophic but the long-life benefit is lost. Drain-and-refill with G05 yellow.
HOAT + HOAT (yellow + yellow)
Fine if both meet the same G05 spec. Mopar yellow plus Zerex G05 plus Motorcraft Gold all coexist without issue. Verify spec on the bottle, not just the color.
Common questions
HOAT yellow flush FAQ
How much does a HOAT yellow coolant flush cost in 2026?
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A HOAT yellow (G05) coolant flush costs $115 to $200 at most independent and chain shops in 2026. Ford and Chrysler dealers typically charge $180 to $260. Mercedes dealers charging for the same G05-equivalent (Mercedes 325.0 spec) routinely quote $280 to $400 because the OEM coolant is more expensive.
What vehicles use HOAT yellow coolant?
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Ford pre-2018 (including F-150, Mustang, Explorer, Escape, Edge, Fusion), Chrysler / Dodge / Jeep / Ram (most models through current production), Mercedes-Benz (using 325.0 or 325.5 spec which is G05-equivalent), and some Volvo and Saab models. Many older European makes also used HOAT yellow as the OEM fill.
What is the service interval for HOAT yellow?
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5 years or 100,000 miles for Ford and Chrysler under normal service conditions. Some Chrysler and Mercedes specifications extend to 150,000 miles for severe-duty applications. Always check the owner's manual for the exact interval and the specific G05 product version your vehicle requires.
Can I use universal yellow coolant as a HOAT replacement?
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Most universal yellow coolants on the US market are formulated to meet the G05 specification and are compatible drop-in replacements. The Prestone All Vehicles, Peak Long Life, and Zerex G05 products all carry G05 approval. Verify the bottle label specifically lists G05 (and the OEM specifications you need like Ford WSS-M97B44-D or Chrysler MS-9769) before using as a replacement.
Is HOAT yellow the same as Mopar HOAT?
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Yes, in chemistry. Mopar HOAT is Chrysler's branded version of the G05 yellow specification. The Mopar product is sold under the Mopar label at Chrysler / Dodge / Jeep / Ram dealers at $20 to $30 per gallon. A G05-equivalent universal yellow from the parts store at $14 to $20 per gallon performs the same job in the same system.
Can HOAT be mixed with green IAT or orange OAT?
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No on both counts. Mixing HOAT yellow with green IAT causes a partial inhibitor depletion that shortens service life. Mixing HOAT yellow with orange OAT (Dex-Cool) creates a chemical reaction that can form gel and clog passages. If a vehicle has been mixed, the right fix is a complete machine flush with chemical cleaner, then refill with the correct G05 yellow.
Why did Ford switch from yellow HOAT to orange OAT in 2018?
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Ford's WSS-M97B44-D spec (yellow HOAT) was replaced by WSS-M97B57-A1 (orange OAT) starting in 2018. The reason was a shift to longer interval performance plus improved aluminum protection for the newer EcoBoost and modular V8 engines. Ford vehicles built 2018 and after take an orange OAT coolant, not the legacy yellow.