hey
i have a 2001 Grand Cherokee Limited. is it alright to run 89 octance or 91??

thank you

 

Depends, if you arent noticing any pinging going up hills 87 should be fine.

 

You'll be absolutely fine with 87.

 

its a limimted 4.7 v8

 

The owners manual should have the answer, there should also be a sticker near the gas cap if a higher octane is needed. 87 is fine though. Higher octane will not increase horsepower.

 

Lol I thought higher octane added a few hps. Man how I've been lied to.

 

My 98 5.9L calls for high octane. if i use anything less it pings and knocks up hills or hard accel. Middle grade is a little better but still pings. And i do notice a differance in performance but milage is about the same.

 

i use 89 cuz its 30 cents cheaper here in iowa

 

91 is the same price in tucson as 87 is here in seirra vista. so i fill up ecvery chance i get in tucson. The only prob is its 75 miles away so i get there may 2 to 3 times a month. Maybe i need to get a big drum and filler up.

 

wuts the diff between the 4.7 and ho4.7? i may just try 89 octane. right in the middle

 

91 octane gas is a sham. 99% of all cars in the US are tuned to run on 87. Its when you start boosting or increasing the compression that octane becomes a MILD issue at best.

 

The 4.7L HO has a retuned intake manifold. Thats all. No changes were made to the internals at all. Cams are the same, pistons, crank...all that is the same between a 4.7L and the 4.7L HO. And again, tuned to burn 87 octane fuel.

 

No kidding, but there are so many people out there that you can not convince otherwise. You may not notice a difference, but the higher octane fuels may create negative effects if anything at all.

 

This is very true.

It'll say in the back of the manual or any quick reference page. Mine says 87, my mom's Subaru says 87, but my high compression BMW says 91.

 

My xj and the wifes tj and her 04 dodge hemi all say 87 the hemi even says not to run 91 in the manual. but the Zj 5.9 book says 91 and it does run better on it. But damn its expensive.