EN 14214 is the European standard specifying requirements and test methods for fatty acid methyl esters (FAME) used as fuel in diesel engines and heating applications. It applies to neat biodiesel — B100 — either as a standalone fuel or as the blendstock for diesel under EN 590. Its most frequently failed parameter is oxidation stability, which since the 2012 edition requires a minimum induction period of 8 hours at 110 °C, measured by EN 14112 or EN 15751.
That 8-hour figure matters, and it is widely misquoted. The original standard set 6 hours. The 2012 revision raised it to 8. A significant amount of online material — including some laboratory and supplier pages — still cites 6 hours. If you are specifying against the current standard, 8 is the number.
What EN 14214 covers
The standard applies to FAME marketed and delivered as:
- B100 — neat biodiesel for use in adapted diesel engines
- Blendstock — FAME intended for blending into automotive diesel under EN 590, currently permitted to 7% v/v (B7)
- Heating applications — FAME for heating oil use
It does not govern the finished blend. Once FAME is blended into diesel, EN 590 applies, and the blend has its own oxidation stability requirement measured by a different method. That distinction is the source of a lot of confusion, and we cover it in EN 15751 and FAME blends.
Key requirements
Generally applicable requirements under EN 14214 (2012 edition and subsequent amendments):
| Property | Limit | Unit | Test method |
|---|---|---|---|
| Ester (FAME) content | min 96.5 | % (m/m) | EN 14103 |
| Density at 15 °C | 860–900 | kg/m³ | EN ISO 3675 / 12185 |
| Viscosity at 40 °C | 3.50–5.00 | mm²/s | EN ISO 3104 |
| Flash point | min 101 | °C | EN ISO 2719 / 3679 |
| Sulfur content | max 10.0 | mg/kg | EN ISO 20846 / 20884 |
| Cetane number | min 51.0 | — | EN ISO 5165 / EN 16715 |
| Sulfated ash | max 0.02 | % (m/m) | ISO 3987 |
| Water content | max 500 | mg/kg | EN ISO 12937 |
| Total contamination | max 24 | mg/kg | EN 12662 |
| Copper strip corrosion (3 h, 50 °C) | class 1 | rating | EN ISO 2160 |
| Oxidation stability, 110 °C | min 8.0 | hours | EN 14112 / EN 15751 |
| Acid value | max 0.50 | mg KOH/g | EN 14104 |
| Iodine value | max 120 | g I₂/100 g | EN 14111 |
| Linolenic acid methyl ester | max 12.0 | % (m/m) | EN 14103 |
| Polyunsaturated (≥4 double bonds) ME | max 1.00 | % (m/m) | EN 15779 |
| Methanol content | max 0.20 | % (m/m) | EN 14110 |
| Monoglyceride content | max 0.70 | % (m/m) | EN 14105 |
| Diglyceride content | max 0.20 | % (m/m) | EN 14105 |
| Triglyceride content | max 0.20 | % (m/m) | EN 14105 |
| Free glycerol | max 0.02 | % (m/m) | EN 14105 / 14106 |
| Total glycerol | max 0.25 | % (m/m) | EN 14105 |
Cold flow is handled separately through climate-related grades. CFPP limits run from +5 °C (Grade A) to −20 °C (Grade F) for temperate climates, and to −44 °C for arctic classes, set nationally by each member state through the national annex. Meeting these on FAME often requires cold flow improvers.
What the 2012 revision changed
The 2012 edition made several changes that still catch people out, because a large amount of online reference material predates it:
- Oxidation stability raised from 6 h to 8 h minimum1
- Monoglyceride limit reduced from 0.80% to 0.70% (m/m)1
- Carbon residue requirement deleted as no longer considered necessary1
- Scope expanded to cover heating oil applications and blends up to B102
- An additional set of climatic classes based on monoglyceride content was introduced, recognising that monoglycerides drive cold-weather filter blocking independently of CFPP2
That last point is underappreciated. A FAME can pass CFPP and still cause cold-weather filter plugging if monoglyceride content is high, because monoglycerides crystallise above the CFPP measurement. This is why filter blocking tendency is a separate concern from cold flow.
Check your source. At the time of writing, the Wikipedia entry for EN 14214 still describes the November 2008 version as current and states it supersedes EN 14214:2003, with no mention of the 2012 edition or the 8-hour oxidation stability limit.3 Several commercial and laboratory pages likewise still quote 6 hours. If a supplier or specification document quotes 6 hours, it is working from a superseded edition.
Always verify limits against the current published edition before contractual use. CEN standards are revised periodically; this table reflects the 2012 edition as amended, and an Austrian national adoption (ÖNORM EN 14214) was published in 2019.
Why oxidation stability is the parameter that fails
FAME oxidises far more readily than petroleum diesel, for a structural reason: the fatty acid chains contain carbon–carbon double bonds, and the methylene positions adjacent to those bonds are vulnerable to hydrogen abstraction. Once a radical forms, autoxidation propagates as a chain reaction.
Feedstock determines baseline vulnerability. The relationship tracks unsaturation:
- Saturated feedstocks (palm, tallow, coconut) — inherently stable, often exceed 8 hours untreated
- Monounsaturated (rapeseed, high-oleic sunflower) — moderate, frequently near the limit
- Polyunsaturated (soybean, sunflower, used cooking oil) — poor, commonly 1–4 hours untreated
This is why the standard also caps iodine value at 120 and linolenic acid methyl ester at 12%. Those two limits are indirect controls on the same underlying problem: too many double bonds.
What failing looks like in practice
Oxidation does not only fail a test. It produces:
- Rising acid number, which corrodes fuel system components
- Peroxides, which attack elastomers and seals
- Gums and insolubles, which plug filters and foul injectors
- Increased viscosity as oligomers form
- Darkening and sediment in storage
A B100 batch at 8.5 hours on despatch can drop below 8 hours during storage and transport. Passing at the gate is not the same as passing at the customer.
How the 8-hour limit is met
Three levers, usually combined.
Feedstock selection and blending. Blending a stable palm-derived FAME with an unstable UCO-derived FAME raises the average. Limited by feedstock availability, price and renewable-mandate feedstock rules.
Processing quality. Residual monoglycerides, free glycerol, methanol and metal traces all accelerate oxidation. Meeting the glyceride limits comfortably rather than marginally improves stability. Trace metals — copper, iron — are powerful pro-oxidants, which is why metal deactivators are used alongside antioxidants.
Antioxidant additives. The standard route. Phenolic antioxidants interrupt the radical chain by donating hydrogen to peroxy radicals. Common actives include TBHQ, BHT, pyrogallol, propyl gallate and BHA, with substantial differences in effectiveness per unit dose.
Typical treat rates run 100–1,000 ppm depending on feedstock and target margin. Response is non-linear: the first 200 ppm typically delivers more hours than the second 200 ppm. Establishing the dose–response curve for your specific FAME is the only reliable way to set treat rate, and it is what our biodiesel antioxidants programme is built around.
Dosing for margin, not for the limit
Treating to exactly 8.0 hours leaves no headroom. Stability declines during storage and distribution, so a batch dosed to the limit will fail somewhere downstream. Common industry practice is to target 10–12 hours at despatch for material facing extended storage, giving a margin against ageing.
EN 14214 versus ASTM D6751
| Parameter | EN 14214 | ASTM D6751 |
|---|---|---|
| Region | Europe | United States |
| Oxidation stability | min 8 h | min 3 h |
| Viscosity at 40 °C | 3.50–5.00 mm²/s | 1.9–6.0 mm²/s |
| Ester content | min 96.5% | not specified |
| Iodine value | max 120 | not specified |
| Cold flow | CFPP, climatic grades | Cloud point, report only |
EN 14214 is materially stricter on stability. US-origin biodiesel meeting D6751 will not automatically meet EN 14214 — the oxidation stability gap alone is nearly threefold.
Frequently asked questions
What is EN 14214?
The European standard defining quality requirements and test methods for FAME biodiesel used in diesel engines and heating applications, covering B100 as a fuel and as a blendstock for EN 590 diesel.
What is the oxidation stability requirement in EN 14214?
Minimum 8 hours induction period at 110 °C, tested by EN 14112 or EN 15751. This was raised from 6 hours in the 2012 edition.
What is the maximum FAME content in EN 590 diesel?
7% by volume (B7). FAME used for blending must itself comply with EN 14214.
Does EN 14214 apply to HVO?
No. HVO is a hydrotreated paraffinic diesel, not a methyl ester. It falls under EN 15940.
How do I improve biodiesel oxidation stability to meet EN 14214?
Select more saturated feedstock, control residual glycerides and trace metals in processing, and dose a phenolic antioxidant — typically 100–1,000 ppm — to a target above the limit to allow for storage ageing.
What is the iodine value limit and why does it exist?
Maximum 120 g I₂/100 g. It caps the degree of unsaturation, which is the structural cause of poor oxidation stability.
Where to go next
Meeting EN 14214 oxidation stability reliably is a dosing question, and the answer depends on your feedstock, your processing residuals and how long the product sits before use.
Rodanco develops biodiesel antioxidants and runs Rancimat dose–response screening on client FAME samples in our laboratory. Where trace metals contribute, our metal deactivators work alongside the antioxidant package.
See also our renewables capability and the wider antioxidants range.
Rodanco B.V. is a specialty chemicals supplier based in Alkmaar, the Netherlands, serving refiners, blenders and biofuel producers across Europe. All formulations are screened in our own laboratory and validated in field application.
Related articles
References
- ÖNORM EN 14214:2019 preview — records the increase of the oxidation stability requirement from 6 h minimum to 8 h minimum, the reduction of the monoglycerides limit from 0.8% to 0.7% (m/m), and the deletion of the carbon residue requirement. ANSI Webstore. https://webstore.ansi.org/preview-pages/ON/preview_ONORM+EN+14214_2019.pdf
- Biodiesel Standards & Properties — on EN 14214:2012 expanding scope to heating oil and blends up to B10, and introducing climatic classes based on monoglyceride content. DieselNet. https://dieselnet.com/tech/fuel_biodiesel_std.php
- EN 14214. Wikipedia (describes the November 2008 version as current at time of access). https://en.wikipedia.org/wiki/EN_14214
- EN 14214:2012 catalogue entry and change summary. iTeh Standards. https://standards.iteh.ai/catalog/standards/cen/3e3109e5-edfa-43f2-9104-f792e2b4309e/en-14214-2012
- Fuels: EU — Automotive Diesel Fuel, on EN 590 and the EN 15751 20 h oxidation stability limit. DieselNet. https://dieselnet.com/standards/eu/fuel_automotive.php
About this article
Written by the Rodanco technical team. Rodanco B.V. operates an in-house laboratory in Alkmaar, the Netherlands, running screening, compatibility testing and tailored formulation work, and a field service team conducting on-site trials and dosing optimisation across European and global energy markets.
Standards notice. Values quoted from CEN standards are given for guidance. Standards are periodically revised and national annexes differ. Always verify against the current published edition before contractual or specification use.
Last reviewed: August 2026