Home & Leisure

Under the Hood: High performance engines require premium grade fuel

Brad Bergholdt, Tribune News Service on

Published in Automotive News

Q: I have a 2015 Infinity Q70. I use premium gas. Do I have to? Is it recommended or is it a marketing trick to pay more? I have always driven Infinitis and have paid for premium. Is it worth it?

They say an Infiniti will run forever if you change the oil regularly. I don't need synthetic oil. Just regular oil is fine. Correct? But what's the interval? I usually go to Jiffy Lube every 3,000 miles. Good practice?

-- Joe in Chicago

A: Your Infiniti Q70 requires premium grade fuel. Checking the filler neck/gas door for a label can confirm this. Many vehicles with high performance engines require premium grade fuel because of its higher octane, which mitigates detonation, a violent form of abnormal combustion. Significant pressure, heat and stress occur when fuel explodes rather than burns in a controlled fashion.

Some car makers merely recommend premium fuel. In this case the engine's requirements are not as high, and the management system is capable of tuning ignition timing and other functions to tolerate lesser grade fuel. If driven under high temperatures or stressful conditions, such as climbing over a mountain pass during the heat of summer, I would absolutely go with the higher grade recommended fuel. If a vehicle doesn't specify premium fuel is needed, and there are no issues with pre-ignition or detonation, using it is a waste of money.

Regarding your oil change question, the Infiniti engine on your Q70 employs special friction reducing coatings on certain parts and a highly sophisticated valve train that benefit from using top-notch oil.

Nissan recommends their branded ($13-ish per quart) engine oil that contains an ester additive and some other high-tech friction reducing tricks. There is considerable debate on whether a good synthetic oil might do just as well at less cost. Infinity recommends changing oil on your Q70 every six months or 5,000 miles.

--Sponsored Video--

What really matters is your driving habits. Extreme cold weather operation, short run times, lots of idling in traffic at higher temperatures, demanding high temperature conditions/towing, and driving in dusty conditions bring down the recommended oil change interval possibly as low as 3,000 miles. Easier conditions and long run times could make a 8,000- to 10,000-mile oil change reasonable. I'm thinking: buy a five quart jug of Mobil 1 extended performance synthetic oil for $30 or $35 and bring it to your shop every 5,000 to 6,000 miles.

Julie and I just arrived in Alaska after enjoying a trouble-free and fulfilling drive up from California, our 17th time exploring the highway. Extensive preparation of the truck and trailer, route planning, and care in avoiding road issues can make this a spectacular road trip! Unlike the old days, the Alaska Highway is 98% smooth paved roadway, with occasional gravel/construction sections, which are reasonably smooth but dusty. The final 100 miles of Yukon and first 100 miles of Alaska roadway are the only rough spots. Frost heaving of the road surface and damaged pavement require slow speed and alert driving. We enjoy finding new "itinerant camping" spots each time, such as along lakes, rivers or smack in front of a glacier. I'll be sure to add some new photos of spectacular sights to the website.

About The Writer

Brad Bergholdt is an automotive technology instructor at Monterey Peninsula College in Monterey, Calif. Readers can contact him by email at Personal replies are attempted. An archive of past columns and additional consumer automotive information can be found at

(c)2019 Tribune Content Agency, LLC

Distributed by Tribune Content Agency, LLC.


blog comments powered by Disqus

Social Connections


Gary Markstein Little Dog Lost Sarah's Scribbles Long Story Short Mike Luckovich Steve Breen