I use both.. Ends up being every other fill. When I go to Costco I fill up on premium. Otherwise regular. 10 years or so. No issues.. I don't really track mileage.

With regular I had knocking so I moved up. Premium was recommended but I wanted to find out for myself.

Anonymous wrote:Lower performance. Modern engines have a knock sensor that detects low octane and will reduce engine output. Most likely to notice it when engine is under strain like going up a big hill.

It doesn’t “reduce” output. It retards timing. That, under unusual circumstances (typically at a part of the powerband you don’t ever use) MIGHT reduce power. Generally though, the caution that it me reduce engine performance relates to MPG.

Anonymous wrote:Is it true you only need it if manufacturer says “required” but not if “recommended?”

Yes, unless you hear knocking, notice performance issues, or notice a drop in gas mileage. Then go to a higher level.

Is it true you only need it if manufacturer says “required” but not if “recommended?”

Lower performance. Modern engines have a knock sensor that detects low octane and will reduce engine output. Most likely to notice it when engine is under strain like going up a big hill.

Anyone ever put regular unleaded when the manufacturer specified premium? What happened???