Is Your Petrol Really E20? Here's How I Check It in 5 Minutes
If you've filled up petrol anywhere in India recently, you've probably heard the term "E20" thrown around — sometimes as a government achievement, sometimes as a worry your mechanic mentions when your bike starts running rough. We get a lot of questions about this at ASES, so I figured it's worth writing down what's actually going on, and how you can check it yourself in under five minutes.
Here's the short version: India has been steadily increasing the ethanol content blended into petrol, moving from E5 to E10 and now toward E20 in many parts of the country. It's part of a genuine push to cut down on crude oil imports and vehicle emissions. Good goal. But it also means the petrol going into your tank today isn't quite the same fuel your car or bike engine may have been designed around a few years ago, and the actual blend can vary more than people expect from pump to pump.
"Is my petrol adulterated?" — the question we actually get asked
Most people don't come to us worried about ethanol blending policy. They come to us asking some version of "is my petrol adulterated?" — usually after noticing lower mileage, a rough idle, a knocking sound, or just a gut feeling after filling up at a pump they don't usually use.
Here's the honest answer: adulteration and ethanol blending aren't quite the same thing, but they show up the same way to a normal rider or driver. Government-mandated ethanol blending is legal and intentional — up to the current permitted percentage. What crosses into adulteration is when the actual ethanol content (or other cheap diluents) goes well beyond what's declared, either through deliberate mixing further down the supply chain or inconsistent blending at some pumps. Either way, your engine doesn't know the difference between "policy" and "adulteration" — it just reacts to whatever ratio is actually in the tank.
So if you're asking "is my petrol adulterated," a simple ethanol percentage check is actually one of the fastest, cheapest ways to get a real answer instead of guessing based on symptoms alone.
Why the ethanol percentage actually matters
A little ethanol in petrol isn't a problem — most modern vehicles handle E10 without any issue. But higher, inconsistent, or unexpected ethanol content can do a few things over time: it can affect rubber seals and fuel lines in older vehicles, it can throw off the air-fuel ratio in carburetted engines, and in some cases it's simply not what you were told you were buying. We've had customers — workshop owners mostly — tell us they started noticing rough idling or corrosion complaints on older bikes and wanted a quick way to check what was actually in the tank before assuming it was a mechanical fault.
That's really the practical value here. You're not trying to run a lab-grade analysis in your garage. You just want a fast, honest read on roughly how much ethanol is in a fuel sample, so you know whether it's worth investigating further.
How we test it (it's simpler than it sounds)
We stock a small calibrated kit called Ethogage that does exactly this using an old, reliable trick — water and ethanol mix together and separate out of petrol, while pure petrol stays where it is. So the test is basically:
- Fill the bottle with water up to the marked water line.
- Add your fuel sample up to the marked fuel line.
- Cap it, give it a good shake for a few seconds, and let it sit for a few minutes.
- Read where the water-ethanol layer settles against the printed percentage scale — it's marked from 5% up to 30%.
That's it. No power, no reagents, nothing that expires. You can do it at home, in a workshop, or right at the pump if you're curious enough to carry a bottle around (some of our customers do).
Who actually needs this
Honestly, most people who buy this from us fall into a few groups: owners of older bikes and cars who are a bit protective of their engines, workshop mechanics who want a quick diagnostic step before they start pulling things apart, and a few petrol pump owners who use it as a basic spot-check on incoming stock. We've also had fleet operators pick up a few kits to keep an eye on fuel consistency across vehicles.
If you're just driving a recent-model car with no issues, you probably don't need to test every tank. But if something feels off, or you just want peace of mind before a long trip, it's a cheap way to rule out one variable.
A couple of honest caveats
This isn't a certified lab test, and we wouldn't pretend it is. It gives you an indicative reading, which is genuinely useful for spotting something unusual, but if you need a result for compliance or legal purposes, that has to go through an accredited lab. Also, results can be affected by how carefully you measure the water and fuel lines and how well you shake the sample — so if a reading looks way off, it's worth repeating the test before drawing conclusions.
We keep a small stock of the Ethogage ethanol test kit at ASES if you want to try it yourself. It's inexpensive, reusable, and honestly kind of satisfying to watch the layers separate the first time you use it.
If you've used one of these before, or you're seeing fuel-related issues on older vehicles you think might be ethanol-related, we'd genuinely like to hear about it — it helps us understand what's actually happening on the ground as this rollout continues.