The approved coolant specification for BMW engines across 1990–2025: G48, HT-12, colour codes, capacities and the mixing rules that matter.
BMW's factory coolant specification is either G48 (blue/green) or HT-12 (green) depending on model year. Both are ethylene-glycol-based, nitrite- and amine-free, and must be mixed 50:50 with distilled water.
Full specification table, variant differences, and the mixing trap explained below.
| Spec | Value |
|---|---|
| Approved Type (pre-2018) | G48 (blue/green) — BMW 83 19 2 282 225 [PLACEHOLDER] |
| Approved Type (2018+) | HT-12 (green) — BMW 83 19 2 450 844 [PLACEHOLDER] |
| Base chemistry | Ethylene glycol + corrosion inhibitors (silicate/borate blend) |
| Mix ratio | 50% concentrate / 50% distilled water — never tap water |
| Typical capacity (N47/B47) | ~8.0 litres (total system) [PLACEHOLDER] |
| Typical capacity (N57/B57) | ~10.5 litres (total system) [PLACEHOLDER] |
| Typical capacity (N63/S63) | ~12.0 litres (total system) [PLACEHOLDER] |
| Change interval (G48) | 4 years / 60,000 miles [PLACEHOLDER] |
| Change interval (HT-12) | 5 years / 80,000 miles [PLACEHOLDER] |
Figures marked [PLACEHOLDER] require confirmation against the BMW workshop manual before this page goes live.
BMW has used two distinct coolant specifications across the last three decades. The changeover from G48 to HT-12 happened gradually across 2017–2019, with some engines using G48 well into 2019.
The 50:50 mix ratio is not optional. Using anything other than distilled water introduces minerals that accelerate corrosion and can block the cooling system — a £15 mistake that can cost a radiator or water pump. Independent specialists we've spoken to consistently report that many owners don't realise BMW's coolant spec changed with the B-series engines: HT-12 is not backward-compatible with G48, and mixing them causes the additives to gel, blocking the heater matrix and radiator [EM-INTERVIEW]. This is covered in full mechanism detail on our thermostat housing failure page and coolant loss without a leak symptom guide.
The coolant specification for your specific chassis and engine code is stamped on the expansion tank (G48) or listed on the sticker under the bonnet on later HT-12 cars. If in doubt, the BMW engine number decoder page can confirm the build date and factory fill spec — Engine Code Decoder. For a definitive answer, the BMW parts system using the last seven digits of your VIN will tell you exactly which coolant was factory-filled.
The coolant specification affects the water pump, thermostat housing, EGR cooler and heater matrix all at once. Using the wrong coolant doesn't cause a single, dramatic failure — it reduces the life of every component in the cooling circuit, and the bill when it all fails together is far higher than the difference between a £20 universal coolant and a £40 BMW-approved bottle. The chemistry is not marketing: the additive package is specifically designed for BMW's aluminium and plastic cooling circuit, and the absence of nitrates and amines is part of the water pump seal life calculation. This is why specialists we've spoken to treat "any green coolant" as a red flag — see our timing chain diagnosis guide for a parallel example of why BMW specification matters beyond the spec sheet.
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Last Verified March 2026Reviewed on schedule, not left stale.
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