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Ethanol in older models

I drive a 2000 Chev Blazer and my husband thinks gas with ethanol will ruin the motor. There is now only one gas station left in town that has regular gas. I secretly put gas with ethanol in the tank when I was on a trip and couldn’t find regular gas - before that tank was empty, the “Check Engine” light came on. What is the solution for older model vehicles and ethanol gas?

10% ethanol shouldn’t be any problem other than it will slightly reduce your MPGs.
Many auto store will read DTCs for free. Please do that and post the code(s) that they read out here. It is unlikely that the check engine light is directly related to the E10 gas you used.

There should be no problem using E10 gasoline in your 2000 blazer. The fuel system/engine is designed to use E10 gas. If you’re using E85 gasoline, that will damage the engine. As far as the Check Engine light, some local auto parts stores will pull the code(s) for free. Get that done to determine what’s causing the Check Engine light to come on.


When I got the oil changed, the guy fiddled around in the fuse panel and the Check Engine light went away. It could very well be a short, but my husband thinks it is because of the ethanol gas.

I bought a 2000 Blazer LT in February 2003. New Jersey switched over to E-10 year round soon after. Other than a drop in mpg, the Blazer and my 1993 Caprice have had no issues with E10. Concerning the “Check Engine”, was the gas cap screwed on all the way? I would prefer gas with no ethanol.

I can’t speak for E15 and would not attempt to use E85 in the Blazer.

Ed B.

If the check engine light comes back on, get the codes read and post them here.

I agree that the 10% Ethanol SHOULDNT be an issue in cars. I can recount for you the ABSOLUTE DISASTER it caused on the waterfront a few years back when they switched to Ethanol fuel on the boat docks.

Everyone was having issues on their boats that year…the older the worse it was.

It seems that Ethanol is an EXCELLENT cleaner…as it cleaned out any old goop or junk that was in my fuel tank in my boat and then tried to pump it up to my carb…what a disaster. Ethanol also binds to water…so it basically cleaned my tank and found any and all of the water in my tank (neither of which caused me any issues before) bound it all together and tried to pump it up to my carb and run my engine…needless to say…It didnt run my engine…and many many other boaters engines.

What happened to me was a double whammy…I never thought my tank had any varnish or gums in there…and there very well may not have been any in my tank…But I CAN say that the 50+ year old tank in the ground at the marina had crap in it…Then the Ethanol went into that old tank and did a cleanup job and filled all of us up with TOTAL CRAP FUEL… WHat a nightmare diagnosing this. They came “Clean” about this after the fact but there were literally thousands of boaters scratching their heads and missing out on the season down in Avalon, NJ… Once I figured it out I made quite a lot of money fixing other peoples boats. Oh yeah the older boats with Fiberglass tanks got hit the hardest…seems ethanol will EAT the resin in the glass and all sorts of nightmares arose in those older glass tanks…what a disaster.

SO for your instance just remember if there is any varnish or gum in your tank and any water the Ethanol will bind to it and try to pump it up to your engine…not good. If you dont have any crap in the tank…you would be fine with a 10% concentration of Ethanol however.

You car is not old enough to worry about that.

Other than a slight drop in fuel mileage and a maybe, plugged fuel filter you shouldn’t have any problems. Given that after many years of e10 the only problems I’ve seen is bad fuel sending units, it seem the e10 will slowly eat away at the sending unit causing the fuel gauge to quit operating.

I wouldn’t worry too much about the fuel filter, if you use your blazer and buy good fuel odds are you don’t have that much varnish in the tank.

The check engine light could be anything after 10 years and is most likely an ox sensor, but post the codes and we’ll try and help.

My opinions are subject to change with new facts.

Is it a 4cyl or 6cyl? If its the 2.2l 4cly it is a flexfuel vehicle. No harm at all (except MPG), in fact you could run E85 if you wanted. However, the 6 was NOT flex, so nothing more than E10. No harm running E10.

My cars are both older than yours and have experienced no problems running on E10. 10% ethanol will not ruin anything on your Blazer.

The CEL came on for some reason other than the ethanol in the gas.

I want to thank you for your post on ethanol and what you’ve learned about it. I have a 1986 Ranger and you may have pointed to a major problem with my bogging down issues. Thanks again and I’ll keep you posted on my findings.

Shouldn’t be any problem, but you may want to change fuel filters after the first tank or two full. Ethanol can loosen gunk in the fuel system which the filter will trap.