How to Get the Most Fuel Economy

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Fuel economy is calculated by distance traveled / fuel consumed. Driving a vehicle less will simply accumulate fewer miles on that vehicle, and does not necessarily change the vehicle's calculated fuel economy. In fact, letting the vehicle sit with fuel in the tank is likely to cause increased evaporative emissions and actually reduce the fuel economy. But I appreciate the attempt at humor.
I like to crack a joke here and there. After I switched to a 180F thermostat and did a grille shutter delete in my RAM 1500, the fuel economy got slightly worse. Unless I run hard or tow a trailer, the oil won't get past about 190F~200F (if it's scorching outside). Driving around town, it will take forever to get to 185F. I switched from Mobil 1 FS 0W-40 to Mobil 1 EP 5W-20, and my fuel economy is awesome now, and that's on 87 octane gas. The owner's manual recommended 89 octane, but that is most likely due to the ridiculous temperatures of 220F+ that this engine was running at. Like many, I am also chasing the best fuel economy possible. Why was I running 0W-40 in there before? To compensate for the ridiculous coolant and oil temperatures while towing. Even a 2000 lbs trailer would bring the temperatures up to ~240F~245F. That's no longer the case.
 
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What's that cost? 2 or 3 times that of other good oil? That's FALSE economy.
That was humor. The placebo effect is crazy. If you look around YouTube there are a few who claim just that, lol. I use AMSOIL driveline fluids, because they are easily available and of decent quality and cost. But I would not spend money on their motor oil.
 
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After I switched to a 180F thermostat and did a grille shutter delete in my RAM 1500, the fuel economy got slightly worse. Unless I run hard or tow a trailer, the oil won't get past about 190F~200F (if it's scorching outside). Driving around town, it will take forever to get to 185F. I switched from Mobil 1 FS 0W-40 to Mobil 1 EP 5W-20, and my fuel economy is awesome now, and that's on 87 octane gas. The owner's manual recommended 89 octane, but that is most likely due to the ridiculous temperatures of 220F+ that this engine was running at. Like many, I am also chasing the best fuel economy possible. Why was I running 0W-40 in there before? To compensate for the ridiculous coolant and oil temperatures while towing. Even a 2000 lbs trailer would bring the temperatures up to ~240F~245F. That's no longer the case.

Are you really talking oil temperature? Why do you think oil temp of 220°F is "ridiculous"? Even 240°F is still trivial.
Though you said you're "chasing the best fuel economy possible" you're doing a frigging lot to make it worse.
 
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Are you really talking oil temperature? Why do you think oil temp of 220°F is "ridiculous"? Even 240°F is still trivial.
Though you said you're "chasing the best fuel economy possible" you're doing a frigging lot to make it worse.
Have you ever owned or messed with any vehicle with a 5.7 HEMI engine?
 
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Is a 5.7 HEMI actually that delicate?
It's not the best-built engine. Heat is a major issue with this engine. It was exacerbated when they implemented grille shutters. This thing cooks itself to death. Exhaust manifold bolts are the first to go. If you're lucky, otherwise, it's always a lifter due to Q&A. Heat is a factor in that it can trigger one of these, or both, to go bad. The 240F I see on the dash extrapolates into much more heat in many engine areas, including the exhaust manifolds.
 
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It's not the best-built engine. Heat is a major issue with this engine. It was exacerbated when they implemented grille shutters. This thing cooks itself to death. Exhaust manifold bolts are the first to go. If you're lucky, otherwise, it's always a lifter due to Q&A. Heat is a factor in that it can trigger one of these, or both, to go bad. The 240F I see on the dash extrapolates into much more heat in many engine areas, including the exhaust manifolds.

Sounds like one of the more reliable Chrysler vehicles if thats all.
 
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To get the best fuel economy is simple.

Drive less.
You are mixing up fuel economy vs money spent on fuel. Driving less has no connection to fuel economy. Spending less money is not the sole purpose you would drive efficiently and want to get high fuel economy.
 

OVERKILL

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Is a 5.7 HEMI actually that delicate?

Nope. We have a small fleet of them at work with about 200,000 miles on each of them, bulk NAPA 5w-20, NAPA filters. These trucks don't have oil coolers and are driven hard and put away wet. Amusingly, we lost one of the most gently driven ones to lifter failure last year (which is a materials issue with the lifter, as discussed in a previous thread, GM has the same issue) while the others are all running fine.

Like many trucks (Ford, Toyota), exhaust manifold stud failure has been a common issue on the DS trucks. It's too early to tell if they've done anything about it on the DT's. We had them all replaced in a package deal a few years ago (almost the entire fleet was ticking) by an amazing tech who I recommended to another member on here who used the updated studs and they've been quiet since.

At least with the HEMI, the manifolds themselves are reusable. On the Ford modular, the manifolds typically crack and getting replacements now has become quite difficult. My dad's passenger side on his Expedition is cracked again and leaking and the Dorman ones don't seem to last like the OE Ford ones do.

We have a 4Runner that belongs to one of the PM's that had the same problem and I guess it's extremely common and a real pain to change them. The OE Toyota manifolds are also insanely expensive, while guaranteed to fail again. He bought a set of stainless headers and had those put on instead, which is supposed to be the more permanent solution.
 

OVERKILL

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I remember reading somewhere (pre-2010) that someone would always turn off their engine when going down hills. Talk about gas saving dedication haha!!

My dad had a friend who did exactly that. Turned off his car when going down a hill, when coasting up to a stop sign or light, it was insane! Dad hated driving with him as did his wife.
 
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My dad had a friend who did exactly that. Turned off his car when going down a hill, when coasting up to a stop sign or light, it was insane! Dad hated driving with him as did his wife.

They called those guys "Hypermilers" . The same guys who draft tractor trailers on the highway.
 
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