plus gas?
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Junior User
Joined: Apr 2004
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plus gas?
i recently switch from chevron reg 87 octane to 89 octane, only having filled up once with it i noticed my mpg went from 330 miles on the tank with reg 87 octane down to 289 miles on the plus 89 octane tank, i also put in a k&n air filter, (the one that last forever), should i have not switched to 89 octane? should i go back to regular, i am just wondering why the mileage went down so much.
Senior User
Joined: Sep 2004
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From: Missouri
You should always use the lowest octane fuel your motor requires. Higher octane fuel has less stored energy per unit than lower octane, however it's not THAT much. You had a significant drop, which leads me to believe it's an ignition issue. Higher octane will account for a small mileage drop, but yours almost has to be an ignition issue.
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Junior User
Joined: Apr 2004
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so i should switch back to the lower 87 octane?
i wouldnt need my truck to be serviced would i?
hmm hope the dang thing doesnt knock and ping when i switch back...
i went ahead and filled up with plus again last night to see if there is a difference in this tank then the last...
i wouldnt need my truck to be serviced would i?
hmm hope the dang thing doesnt knock and ping when i switch back...
i went ahead and filled up with plus again last night to see if there is a difference in this tank then the last...
Senior User
Joined: Sep 2004
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From: Missouri
If it wasn't knocking and pinging before you switched, it won't when you go back. I'd suggest going back to 87 octane. Cheaper per gallon, plus better mileage. The only reason to use higher octane fuel is if the compression in your engine requires it to prevent knocking and pinging. None of these trucks (except lightning and HD I believe) require any higher than 87. You should be fine. See how this tank of 89 goes, and if it's still bad, switch back to 87. Just keep in mind, 89 isn't doing anything more for your motor than 87 is, just costing you more money.
Elder User
Joined: Apr 2004
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From: Indianapolis, IN
I was told by the service adviser on my 04 that 89 burns too hot for the 4.6L engine and that I should ONLY use 87.
This is with pure dino based petrol of course. When alky is added to the dino it affects the octane number a bit. I was informed by another tech (my nephew) that 89 with alky is about the same as 87 in pure dino.
This is with pure dino based petrol of course. When alky is added to the dino it affects the octane number a bit. I was informed by another tech (my nephew) that 89 with alky is about the same as 87 in pure dino.
Postmaster
Joined: Aug 2003
Posts: 2,977
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From: South Texas
It's hard to calculate acurate MPG from just one tank full and then compare it to previous MPG, just to many variables. If you had no knocking/pinging with the 87, why spend more money for 89?
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Junior User
Joined: Apr 2004
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well...
im now at half a tank left, only at 130 miles on the odometer... BUT went to check tire pressure this morning out back and my tires were all screwed, there supposed to be at 35 all around, well the front 2 were at 27 for some reason, and the back two were at 40... i think the people that changed oil last time didnt know how to read the psi right... :-\ so i am really beliving that is a playing factor in this whole horrible gas milage, so hopefully the mileage well get better since i fixed tires pressure this morning, ill let yall know... i also believe i will be going back to 87 octane, i mean the truck runs great at 89 just the gas milage is worse for some reason, but now i believe the tires were one of them....