russianDude

we have Maxima 2003 in our family, and owners manual recommends 87 AKI (Reserach octane number 91 )
Can I use regular or need premium gas?
Still trying to figure out what gas to use on Nissan Maxima 2003....

russianDude

What the hell is Anti-Knock Index(AKI)????
If it says minimum AKI 87, does it mean I can get cheapest gas on the gas station??

scalbert

There are two measurements for octane, RON and MON and in the USA we use a formula of ( RON + MON ) / 2 to determine the pump octane rating.

Below is an portion of an article explaining the two:

Octane Article

Gasoline pumps typically post octane numbers as an average of two different values. Often you may see the octane rating quoted as (R+M)/2. One value is the research octane number (RON), which is determined with a test engine running at a low speed of 600 rpm. The other value is the motor octane number (MON), which is determined with a test engine running at a higher speed of 900 rpm. If, for example, a gasoline has an RON of 98 and a MON of 90, then the posted octane number would be the average of the two values or 94.

russianDude

For CLS the manual specifies minimum 91 RON ? But at gas station we see (RON+MON)/2.
Then how do we know what gas to use in CLS?

scalbert

The MON will normally be slightly lower so it is safe to assume if the RON is set a minimum of 91 for a vehicle then by putting in equal USA rating is fine. We never see the two values, it is only an average. So take the maximum RON value and go with that to be sure or slightly lower will most probably be fine...

EricL

http://www.powerchipgroup.com/articl...age%20one.html

russianDude

Thanks Eric, you are always helpful!

So CLS manual specifies minimum 91 AKI ? or RON?

russianDude

I think I found an answer:
"To reduce consumer confusion over different octane numbers, the USA passed laws so that AKI is the octane rating shown on pumps at petrol stations in that part of the world. Because of this it is also sometimes called the Pump Posted Octane Number."