what fuel octane do you run in your 4.0 i6 and why?
87. It's the cheapest and the 4.0 is a 35 year old design that does not require anything higher for performance. Anything more than 87 is just wasting money.
thx for your response. i was making sure because ive heard mixed responses.
Don't use 90 octane. Just use Unleaded 87 octane. Using a higher octane fuel is only more expensive, and instead of conserving fuel, it will only burn/use it faster. The inline 6 was only meant to have 87, and it could possibly overwork your engine if you try and go higher. Besides, 87 is the cheapest... why spend more?
I was told by a mechanic to use only reg (85 OR 87 OCT) and not to use the 10% ethenol as this causes the senors to assume that the engine is running lean and will increase the fuel consumption until the 02 sensor is satisfied. I have a 99 with 83K and has not had anything but regular in it. Still runs exceptionally well.
i live in sweden and the low octane here is 95,i run my grand cherokee laredo 4,0 on this,no problems,87 or 89 octane can be had in former east europe or russia,but not in the west,95 gives you a lot of pulling and towingpower
Higher octane helps with fuel consumption unlike what some say, higher octane burns slower
4.0 has dish type pistons and lower compression. In my opinion 87 octane is perfect for a 4.0's factory compression.
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