Many gas station chains here in Central Florida have indicated that they will increasingly use ethanol in their gasoline. The Owner’s Manual of my new Nissan 350Z makes it clear that I should use only High Test gasoline in this vehicle.
Can I safely use a gasoline-ethanol mixture in my 350Z without damaging the engine?
Yes. Your vehicles engine was designed to run on a blend of up to 20% ethanol in the gasoline. This is in anticipation of many states upping their fuels to E20.
Tester
Read your owner’s manual. It will tell you how much ethanol the car can tolerate.
I suspect you can download all of the manuals from Nissan’s web site. Usually they are in Adobe Acrobat format (pdf extension). Rather than fumble with paper, you can search for a key word like “gasoline” or “fuel” and go straight to the information you need.
There are two widespread ways to increase the octane rating in gasoline. One is to add MTBE and the other is to add ethanol. MTBE is on the way out due to soil pollution concerns if gas station storage tanks leak. You have probably been using it for a while now and the state just forced gas stations to post a notice that their gas contains ethanol. I agree with Tester that E20 is common and of no concern.
I would suggest following the instructions from Nissan. If they say High Test use High Test. Did you read anything from them about ethanol? That is a different matter totally. It may or may not be in High Test gas or for that matter it may or may not be in regular.
What year is your car? The owners manual will state whether or not you can safely put a mixture in your car. Some say 15% max but you could probably use 20% in these. I don’t think this issue is related to high test versus regular.