View Full Version : 88 octane in Minnesota and Wisconsin

03-14-2018, 10:54 AM
Hello enthusiasts

I am a (generally) happy owner of a 2008 Charger RT here in Wisconsin and
I make my living driving a fuel tanker in Wisconsin and Minnesota. Over
the last couple of months I have been delivering what is marketed/labelled
as oxy 88. This fuel is cheaper than regular 87 and it is replacing 89
octane as the mid grade option at certain gas stations; what isn't
widely advertised is that this fuel contains 14.5% ethanol. In fact when
I haul this product from the refinery it has a different UN number; any
gasoline product with 10% or less ethanol mixed in is UN 1203 whereas this
88 octane is UN 3475 (the same UN number as e85).

Since my 5.7 recommends a minimum of 89 octane I am hesitant to use this
new product; I am concerned about the knocking and/or pinging that may
arise from putting it in the engine. As I am sure most of you would be.

I'm not going to address what fuels you should put in your vehicle, I
suspect that if you follow what the owner's manual recommends you'll be
fine (At least in an unmodified engine). The easiest solution would be to
use straight premium (91, oxy 91 or oxy 93), this however can get a bit
expensive if your vehicle is a daily driver like mine. Of course there are
gas stations that are still selling oxy 89, you'll just have to find them.

That being said, here is what you can do if you are faced with limited
options at the fuel pump: make your own 89. First of all please realize
that 89 octane with 10% ethanol is not refined at that octane rating; it
is a mixture of what is called subgrade, premium, and ethanol. At the
loading terminal 89 octane is 10% ethanol, 48% subgrade, and 42% premium.
87 octane is 10% ethanol and 90% subgrade (Premium is straight premium with
a few additives). So I have been putting in roughly 7 gallons of 91
when I fill below a quarter tank and filling the rest with 87 octane. As
you drive the fuel will mix in the tank (it does in the fuel tanker).