Which Fuel For 3.8 V6

[Tog]

I only run 98 in both my KJ &Kk the biggest difference I notice is in where I buy from 7-11 seems to give me the best mileage I have had some small independent servos that only give me half the mileage of others

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[MightyMouse]

Us manual says 91 octane.... Au manual says 91 octane yet 91 US is 95 Au... see a problem ?

[Banshee]

They don't use RON, they use 'pump' which is (RON+MON)/2. The average of Research and Motor octane ratings, which as you said is lower by 4-5 points.

But I thought the US manual said 87?

[Kiwi Jeeper]

Originally Posted by Banshee

They don't use RON, they use 'pump' which is (RON+MON)/2. The average of Research and Motor octane ratings, which as you said is lower by 4-5 points.

But I thought the US manual said 87?

I remember it was 87 in US as well, and your octane rating difference is correct as well.

[mudpig]

We have to use minimum 95 in our 3.8. Using 91 our engine has more ping than Beijing.

I threw the manual out after the 3 years. Please understand that using the Manual as gospel is fine to get through your warranty period but the manufacturer doesn't give a shit if the engine blows 6 months after that.
Why?
We use a heavier weight oil than the manual states as well. Don't forget the US gets far colder than we do.
Who benefits from the sale of replacement engine parts because you're still using 5-25w or 5-30w oil in your your 150,000km engine.



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[Banshee]

Thin oil doesn't wear it out, it just uses a little less fuel and burns the oil. The "uses less fuel" is important to the US to get Jeep through the CAFE* requirements.

While 91 is the effective min here, using E10, (94RON), 95 or even 98 didn't help me with the pinging. The snorkel fixed that by lowering the intake air temp to ~5C over ambient from 15-25 over. I can now use 91 if I need to. (But e10 is cheaper & the mileage isn't that much worse.)


*Combined Average Fleet Economy