5.0 V8 Fueling and Efficiency Questions

[rolledover]

I remember being glum after I watched it the first time, and I don't have the courage to watch it again.

Nonetheless, I am heartened by the number of high mileage LR4s that are appearing on the forums now and then. Mine has around 112k miles now, so it should have a long time left.

I'm at 173k. I had to replace a burnt exhaust valve at 168k but it has been great since then.

 

[avslash]

I generally run premium but recently did a couple tanks of regular.

Correct me if I am wrong, but the benefit of a higher octane rating is increased resistance to pre-ignition or detonation. Since our engine management systems include a knock (detonation) sensor (LR008877), I would expect the ECM to ****** timing when knock is detected.

Will it make less power? Yes. Will it damage the engine? Not IMO if the ECM is functioning correctly.

 

[ktm525]

Question for all of you 5.0 V8 owners out there: Is everyone putting in premium in their whips or is anyone using mid grade without any issues?

Also, what is your average fuel efficiency? This question stem last from deciding whether I send my injectors in for servicing.

I'm averaging about 16.5 mpg mixed between hwy and city with premium fuel.

Remember as altitude increases the octane number that is acceptable drops. I noticed Denver in your signature so Likely a 89-91 fuel would be fine. In Calgary at 3800' our premium is only 91 at most places not 93.

 

[f1racer328]

I generally run premium but recently did a couple tanks of regular.

Correct me if I am wrong, but the benefit of a higher octane rating is increased resistance to pre-ignition or detonation. Since our engine management systems include a knock (detonation) sensor (LR008877), I would expect the ECM to ****** timing when knock is detected.

Will it make less power? Yes. Will it damage the engine? Not IMO if the ECM is functioning correctly.

I generally always run premium (91 in AZ) as well, and I agree with the knock sensor reta-rding the timing.

I think the quality of the fuel is going to play a more important role over time. I almost always fuel at a station with Top Tier fuel (Costco in my case.)

 

[ftillier]

I guess it depends on whether the ECU tries to advance timing as far as possible, even with premium, and then backs off as it detects knocking. I would assume that with proper premium, the ECU would be at its "normal" settings (full advance) and expect zero knock. So while it might pull back timing for lower grade fuel, it does so in a reactionary manner, and would keep trying to have it as far advanced as possible - that means there will be some knock. I don't know if minor knocking is detrimental, my gut feel is that it would lead to additional wear and tear due to uncontrolled pressure waves in the cylinder chamber. For lack of better knowledge, I stick to premium if it's available.

 

[LR4Slavo]

Remember as altitude increases the octane number that is acceptable drops. I noticed Denver in your signature so Likely a 89-91 fuel would be fine. In Calgary at 3800' our premium is only 91 at most places not 93.

I've heard that before but didnt know how that applies, whether mid-grade (89) is alright, but then again I'm also not super keen at saving a few bucks at the pump and potentially have a major issue down the line. We're at a minimum of 5000' of elevation

 

[cperez]

I’ve committed to premium fuel (Top Tier only unless in a pinch) and the lavishly priced golden nectar Castrol oil. I think my average mpg is in the 16-17 range.

Every now and then my wife will comment on a gas station that had a low price for regular. Based on my reaction I think she’s figured out that I have no need for that information.

 

[Kelly J Ragsdale]

I use only premium in my V8. I live at 5,000 ft and we only have a few gas stations that even offer 89 octane. It is 87 or 91 so I go with the 91. My fuel economy is decent but haven't tracked it in detail.

 

[Bryan Jones]

I only use Shell premium, almost 140k miles on the clock, average about 10 mpg. But I also run 35's on steelies and my wife's uses the truck to run errands and pick up/drop off the kids

 

[boaterguy59]

I'm at 173k. I had to replace a burnt exhaust valve at 168k but it has been great since then.

!70k on my 2011. Run regular here at sea level. Don't beat on it. Average about 15mpg. Truck is amazing. Didn't buy it for MPG's. Would note that my '07 XK convertible averages 25!!