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 donít need
synthetic oil. Just regular oil is fine. Correct? But whatís the
interval? I usually go to Jiffy Lube every 3,000 miles. Good
ó 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 engineís
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 doesnít 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.
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.
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. Iím 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.