The Real Risk on a BYD Coolant Job
When a workshop takes on a BYD cooling job, the first risk is not technical difficulty. It is putting the wrong fluid in. Across BYD’s own handbooks, the coolant is described using at least four different names, the fill capacity varies by a factor of more than three, and the freezing point quoted is not consistent between models.
This page pulls the specification sections out of all ten official English handbooks and lays them side by side, so that one table answers “what goes in this car, and how much.” It is written for the question a technician actually asks: what is the BYD coolant type and BYD coolant capacity for the car on my lift?
The Headline: Four Names, One Chemistry
Here is every description BYD uses for coolant across the current range:
- Long-acting organic acid coolant
- Glycol organic acid antifreezing coolant
- Ethylene glycol type long-acting anti-rust antifreeze
- Ethylene glycol type anti-rust antifreeze
Read past the naming and the picture is simple. Glycol is ethylene glycol. Add an organic acid corrosion-inhibitor package and you have an ethylene glycol based OAT (organic acid technology) long-life coolant. The four names reflect different translation batches across model handbooks, not four different products.
That is the reassuring half. The next part is where people get caught.
Freezing Points Are Not Interchangeable
Most models specify -40°C. But the Atto 3 handbook lists -25 / -40, which tells you BYD ships different concentrations depending on market or configuration. Freezing point is a proxy for glycol concentration, and concentration is exactly what determines the protection level.
Practically: do not assume that because the fluid you have on the shelf is “BYD coolant” it is correct for the car in front of you. A -25°C fill topped up with -40°C fluid changes the mix. BYD’s own instruction is unambiguous on this point — the coolant must always be of the same specification as the original, with no admixture, and different brands and types must not be mixed.
Coolant Type and Capacity, Model by Model
| Model | Coolant specification as published | Capacity |
|---|---|---|
| Atto 1 (2025) | -40°C long-acting organic acid coolant | Auxiliary water tank 3.0 ± 0.2 L / 3.5 ± 0.2 L |
| Atto 2 (2025) | Glycol organic acid antifreezing coolant, -40°C | Motor coolant 3.7 ± 0.5 L |
| Atto 3 (2025) | Glycol organic acid coolant, -25 / -40 | Motor coolant 3.5 ± 0.5 L |
| Dolphin (2023) | Glycol organic acid coolant, freezing point -40°C | Motor coolant 3.1 ± 0.2 L / 3.3 ± 0.2 L |
| Seal (2025) | Glycol organic acid long-acting anti-rust antifreeze, -40°C | Motor coolant 4.8 ± 0.2 L / 5.3 ± 0.2 L |
| Seal 6 (2026) | Ethylene glycol type anti-rust antifreeze, -40°C | Motor coolant 3.7 ± 0.5 L / 5.5 ± 0.5 L |
| Sealion 5 (2025) | Ethylene glycol type long-acting anti-rust antifreeze, -40°C | Engine coolant 7.0 ± 0.2 L • Motor controller coolant 4.35 ± 0.2 L |
| Sealion 6 (2024) | Ethylene glycol type anti-rust antifreeze | High temperature circuit 7.5 ± 0.5 L • Low temperature circuit 7.0 ± 0.5 L |
| Sealion 7 (2025) | Glycol organic acid long-acting anti-rust antifreeze | Motor coolant 6.05 ± 0.2 L / 6.65 ± 0.2 L |
| Shark 6 (2024) | Ethylene glycol antifreeze, -40°C | Engine coolant 8.8 ± 0.5 L • Motor controller coolant 10.1 ± 0.5 L |
Where two figures appear for one model they correspond to different drivetrain configurations, not a tolerance range. Confirm the variant before ordering fluid.
Two Circuits or One — This Is the Practical Difference
The table above separates cleanly into two groups, and the split has nothing to do with model year.
Single-circuit battery electric models
Atto 1, Atto 2, Atto 3, Dolphin, Seal, Seal 6, Sealion 7 list a single coolant figure — the BYD motor coolant loop. There is no engine, so there is no separate engine circuit to fill.
Two-circuit DM-i plug-in hybrid models
Sealion 5, Sealion 6 and Shark 6 list two independent figures because they have a BYD engine coolant circuit as well as an electric drive. The two circuits are separate systems with separate fill volumes, and on the Sealion 6 they are even labelled by operating temperature rather than by component.
This is the mistake that costs the most time: treating a DM-i car as if it were the same as a pure EV and filling one circuit. On a Shark 6 that is a 8.8 L engine circuit and a 10.1 L motor controller circuit — two very different numbers, and neither one is the other.
Reading the Numbers in Practice
A few observations that fall out of the table:
- Capacities span 3.0 L to 10.1 L. Buying “a couple of litres” without checking the model is not a plan.
- The tolerance bands are wide. Values like ± 0.5 L are normal, so a fill slightly off the nominal figure is not automatically a fault — but a circuit that needs a litre every month is a leak.
- A/C refrigerant is a separate specification. The Dolphin lists R1234yf at 1000 ± 20 g alongside the coolant; do not conflate the two systems when ordering.
- Level is checked on the expansion tank, between MAX and MIN. All the handbooks use the same wording, and all of them warn not to open the tank while the motor is still hot — the coolant can eject and cause burns.
What BYD Requires You to Do
Three instructions recur across the handbooks, and they are worth stating plainly because they define the standard of care:
- Same specification as original, no admixture. Not “equivalent” — the same specification.
- Never mix different brands or types. Colour matching is not specification matching.
- Refill to MAX if below MIN, and check the system for leakage. Low coolant is a symptom to investigate, not just a top-up task.
On battery coolant specifically, one handbook adds an observation that surprises people: the battery coolant can fade in colour when exposed to strong UV such as direct sunlight. Colour drift on a cover that has been off in the sun is therefore not necessarily contamination — which is exactly why the specification, not the colour, is what you match.
Stuck on a Fault Code or a Locked Module?
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Companion Pages: Putting These Documents to Work
The manuals above are the source. These pages are the extracted, workshop-ready versions of what is inside them.
- BYD high voltage shutdown procedure — Before touching anything on the high-voltage side — both disable methods, the 60-second de-energising window, and the fire and submersion procedures.
- BYD battery fire and thermal runaway response — A flooded or collision-damaged car arrives — the 24-hour cooling figure, the 45-minute release window, the 15 m isolation distance, and the four methods BYD rules out.
- BYD Dolphin fuse box diagram — Chasing an electrical fault — all 53 under-hood and 31 dashboard positions, and the component each one protects.
- BYD warning light meanings — A customer reports “a light came on” — which lamps mean stop now, which mean book it in, and the electric-only symbols.
- BYD Atto 3 service schedule — Taking a service booking — every interval, the four items with independent replacement cycles, and the severe-duty tightening.
Source
Compiled from the vehicle specification sections of ten official BYD English-language owner’s handbooks: Atto 1 (2025), Atto 2 (2025), Atto 3 (2025), Dolphin (2023), Seal (2025), Seal 6 (2026), Sealion 5, Sealion 6 (2024), Sealion 7 (2025) and Shark 6 (2024). Specifications are reproduced as published. Always confirm the specification and capacity against the handbook for the exact model and variant on the lift before filling.