Karnataka E20 petrol test dispute explained: What the two sets of results show

Karnataka reported ethanol readings up to 31.2%. The Petroleum Ministry cites separate tests within the E20 range and says joint testing is needed.

#Karnataka E20 petrol test#ethanol blending Karnataka#E20 petrol standard#IS 17021 ethanol testing#oil marketing company test results

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By Ashutosh

Automotive Journalist

Source: Maxabout.comPublished Tue, Nov 10, 2026, 02:58 PM IST

Karnataka has reported finding up to 31.2% ethanol in selected petrol samples, above the 19% to 21% range specified for E20 under IS 17021. The Ministry of Petroleum and Natural Gas disputed the testing procedure on 7 November 2026 and cited a separate set of 56 Karnataka samples that measured between 19% and 20%. Public-sector oil marketing companies have asked for joint sampling and independent retesting. The dispute remains unresolved.

What Karnataka and the oil companies reported

Test exercise	Reported result	How to read it
Karnataka’s October exercise	Selected samples reportedly exceeded the E20 range, with a reading of up to 31.2%.	The oil companies questioned how the samples were collected and how the laboratory measured ethanol.
Survey cited by the Petroleum Ministry	56 Karnataka samples measured 19% to 20%. All 893 samples across 27 states and union territories were reported within the 19% to 21% range.	The survey shows what was found in those samples. It does not establish what was in the samples Karnataka flagged.

Karnataka E20 dispute infographic showing the state’s reported 31.2% reading and the oil companies’ results from 56 samples — Karnataka and the oil companies reported different ethanol readings from separate sampling exercises. The oil companies requested joint testing.

Why the ethanol test method matters

IS 17021 sets the specification for E20 petrol. The ministry said that when laboratories use the gas chromatography methods it cited, they must dilute the sample in a 1:1 ratio with petrol free of oxygenates and correct the result using a certified E10 reference material. The ministry said the certificates cited by Karnataka did not identify the full test method or show whether those steps were followed. That leaves an open question about how the reported readings were produced.

A joint retest could establish whether the parties can reproduce an above-limit reading using the same procedure. Both sides would need to document where and when samples were collected, which retained samples correspond to those draws and how the laboratory measured ethanol. Fresh samples could show what a station sells today. Retained samples, if available and suitable for testing, could help resolve the earlier readings.

What this means for motorists

The reports do not establish how widely any above-limit fuel was sold or document vehicle damage from the samples in dispute. To check E20 compatibility, look for the fuel specification in the owner’s manual or ask the manufacturer about the exact model and year. A nationwide survey cannot answer what was in a particular tank. The next meaningful update is a joint test result that identifies the samples and the method used.

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