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The E20 Chloride Contamination Controversy, Explained

A leaked letter, a withdrawal, a large rebuttal, and what is still actually unknown.

Since August 2026, a second controversy has run alongside the ethanol-compatibility debate: claims that E20 petrol itself is contaminated with high chloride levels and excess moisture, separate from anything to do with ethanol tolerance. This is a different issue from the rest of these guides, worth understanding on its own terms — because the evidence is genuinely contested, and most coverage of it has picked a side rather than laid out what is actually known.

What was actually claimed

The Society of Indian Automobile Manufacturers (SIAM) wrote to the government flagging chloride contamination in E20 petrol, reporting levels of up to 350 mg/kg in some samples, and stating that chloride had also been found in damaged vehicle components and in fuel drawn directly from affected vehicles' tanks. The letter was not made public by SIAM — it leaked. In the days that followed, media coverage of the leak cited a higher figure, 500 ppm, which appears to have originated from reporting on the letter rather than from the letter's own numbers. SIAM subsequently issued a clarification and effectively withdrew the letter.

The oil companies' response

Indian Oil, BPCL and HPCL ran a joint testing programme in response: over 100 samples from refineries, ethanol samples from 80 distilleries, more than 80 samples from depots and terminals, and over 160 samples from retail outlets — more than 1,000 samples in total across the supply chain. Reported chloride levels were 0–3 ppm throughout, well below the claims in circulation. The OMCs stated there was no scientific evidence to support the contamination claims, and the Oil Minister described the controversy as manufactured.

Where that leaves things

Two things are both true. SIAM withdrew its letter, and its 350 mg/kg figure was never independently verified in public. The OMC testing programme was large and its methodology was disclosed in reasonable detail, and it directly contradicts the higher figures that circulated. Neither of those facts fully resolves the question: SIAM represents manufacturers who examined damaged vehicle parts, which is a different kind of evidence than supply-chain sampling; and no fully independent, third-party laboratory result is publicly available on either side. Treat both sets of numbers as claims from interested parties rather than as settled fact.

One credible middle position, from Autocar India editor Hormazd Sorabjee, is that contamination — not E20 blending itself — is the more immediate concern, and that it predates ethanol blending entirely. His reasoning is mechanical: ethanol is hygroscopic and absorbs water more readily than petrol, groundwater in India often carries chloride, and where water gets into the fuel supply chain, contaminated fuel can introduce chlorides into an engine. His caution is also worth repeating exactly: if chloride levels go beyond a certain limit, whatever ethanol-compatibility a fuel has stops mattering — contamination can affect any vehicle, not just ones sensitive to ethanol.

What this means for ethanol-free fuel

If the contamination pathway genuinely runs through water ingress, then fuel that does not absorb water the way ethanol blends do is less exposed to that specific mechanism. That is a real argument in favour of XP100, poWer100 and Speed 100 beyond the ethanol-compatibility case the rest of these guides make. It is not a claim that these grades are immune to contamination — any fuel can be adulterated or contaminated at a specific outlet, and no grade substitutes for buying from a source you trust. It is a narrower claim: one specific contamination pathway is less likely with a fuel that does not absorb water as readily.

Don't take this as proof E20 is unsafe, and don't take the OMC testing as proof the concern was baseless. Both would be overreading a still-disputed story. What can be said is that the debate is real, unresolved, and worth tracking rather than dismissing in either direction.