No, it will not mess anything up. Just switch back to Premium when you normally fill up.

 

Thank goodness

 

Thank goodness

 

Hmm check engine light came on today when driving for 15 min I let warm up for like 5 min you think it could have been a Mister fire caused by me putting mid grade gas in? I'm getting the codes checked tommrow, o reallys do the code checks? Hmmm that sucks.
98 disco 188xxx

 

This will be a common task. You may want to invest in your own Ultra Gauge, which reads and resets standard codes, and displays them at your selection, and even provides you-decide alarm points (like coolant temp). See UltraGauge Automotive Information Center and OBDII Scan Tool About $70.

If you decide on a code reader, get one that is also a scanner, in that it displays live data. Don't worry about the "stored fix information for 85,000 vehicles", you just want the code number so you can look it up in the RAVE or supporting ECU manual.

Some codes happen at once, others may require repeat of conditions on two or more drive cycles (crank up from cold).

Might be a misfire, but there are so many other things and this truck is new to you, so best to get it read.

 

If you are that concerned about it, just go top off the tank with premium to boost the octane a little. But a single tank should not cause the CEL to come on. The UltraGauge is a good gauge/scanner to get.

 

Depends on if it's detonating or not.