Why does your car start less well on ethanol in winter?
To sum up:
If your car converted to ethanol (E85) has more difficulty starting as winter approaches, this is a normal and temporary phenomenon.
The immediate solution: add 5 to 10 litres of SP95-E10 to your tank, or fill up the tank as soon as winter E85 is available.
The fuel sold at petrol stations changes composition at this time of year, and this higher petrol content makes cold starts easier.
E85 is not the same all year round
Superethanol-E85 is a fuel that changes with the seasons to adapt to outside temperatures.
Two grades are marketed:
| Grade | Period of sale | Ethanol content | Target |
|---|---|---|---|
| E85 summer | 1 May to 30 September | Up to 85% ethanol | Designed for hot weather |
| E85 winter | from 31 October to 15 March | Minimum 60% ethanol, so up to 40% petrol | Favours cold starts |
Between these two periods, there is an inter-season phase (1-31 October and 16 March-30 April) during which oil depots and service stations gradually switch from one grade to the other.
Why start-ups become more difficult in autumn
During the transition period, some stations are still distributing summer E85, formulated for hot weather.
But ethanol is less volatile than petrol in cold weather: it ignites less easily, which means :
- a longer or hesitant start,
- unstable idling for the first few minutes,
- and even slight jerking when cold.
This is not a problem of engine reprogramming or a mechanical fault: it's simply the chemistry of the fuel changing.
What should you do if your car doesn't start properly on E85?
According to the official recommendations of the Collective for Bioethanol and Shiftech field experience:
- Before 31 October or if your tank still contains summer E85, add 5 to 10 litres of SP95-E10.
→ This increases the proportion of petrol in the mixture and facilitates cold combustion. - After 31 October, refill with a full tank of winter E85.
→ The fuel will be automatically adjusted for low temperatures. - avoid very short journeys when cold: leave the engine running for a few moments to stabilise the mixture.
- Check your spark plugs and battery: a tired ignition accentuates the phenomenon.
A phenomenon that has no effect on your engine
The change in grade of Superethanol-E85 is provided for by the regulations and taken into account in all our FlexFuel Shiftech maps.
There is no impact on reliability, consumption or performance: the phenomenon is temporary and not serious.
Our calibrations are designed to automatically manage variations in ethanol percentage (from 60 to 85%), whatever the season.
In a nutshell
| Symptom | Probable cause | Solution |
|---|---|---|
| Slow or failed cold start | Mixture still "summer | Add 5 to 10 litres of SP95-E10 |
| Unstable idle | Fuel too dry or cold | Allow engine to warm up |
| Recently converted vehicle | More sensitive to cold | The next fill-up corrects the problem |
"These symptoms do not affect the quality of your conversion or the Shiftech calibration.
They disappear as soon as the winter refuelling is done."
Shiftech advises you
FAQ - Cold start and E85 ethanol
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