Diesel vs gas......................

Madhatter1 wrote:
Ace, you make more sense than others on this thread, Sorry if I took you as Pro gas only. I have a question since you seem to have experience in many configs. If you haul a heavy load with a newer gas engine can you use 87 like others say? If you do can you feel any loss in power as the engine prevents knocking. I am used to running 89 or higher hauling but I have not owned a gas engine since 96. Trying to clear up my own misconception if I have one. When figuring out $ per mile the grade of gas needed will make a difference. Which grade would be the one to use for hauling? Curious, but still gonna stick with my diesel.

I recently got back from a 5000+ mile road trip pulling a 37'5th wheel. Our truck is a 03 F250 with a V10, auto, 2WD and 3.73 gears (king ranch short bed now with 97k miles). The trailer, when loaded, is light and only was only about 9600 lb at it's heaviest on this trip. I almost installed 4.30's the week before we left but decided to save the money and find out how well it towed.

I drove almost exclusively with OD off. Realistically, I could have driven many areas with it on but didn't. Mileage was directly proportional to the speed - for every 1 mph increase in speed, the mpg dropped 1/10. The only time I tried to get good mileage was between Northern California and the border of Utah/Wyoming. At 58 mph, I got 9.5 mpg. After that, I just started driving a little faster and the drop in fuel mileage was linear. I also didn't try to over work the engine or tranny so if I hit a grade, I'd wouldn't bury the throttle. I'd lift to prevent it from downshifting and winding out the V10. Sooner or later, it would slow down and I'd have to shift into 2nd and just hold the rpms at 3000, unless the grade decreased. If it did and I could increase the speed, I'd upshift and give it a little gas. The result was that I climbed hills slower than some of the other trucks. Big deal - I wasn't driving 70 mph to begin with. The fastest I ended up setting the cruise control was about 63 mph although I would increase my speed to 65+ prior to hitting a hill, as long as there wasn't any traffic around that I'd impede by speeding up and then slowing down.

The only time I had great hill climbing performance was on 80 driving towards Laramie. We hadn't yet hit the grade going up over the pass but the elevation wasn't too high and the temps were low, 17 degrees (it hit 3 degrees that night while we were sleeping). That was one of the few times that the low temps really added noticeable power. I was able to stay on the throttle without any sudden downshifts and the truck pulled up the hill at 63 without any problems. I did this up until the warning lights that slowed us down to 40 mph (bad weather). Coming down the grade was a bit bizarre though. I had to stay on the gas just to go 50 to 55 and the only explanation I have been able to come up with was the low temps and how it must have affected the tire pressures, along with tightening up some of the lubricants on all the rotating assemblies. Coming down a hill without a headwind and having to stay on the gas instead of watching your speed and lightly using the brakes was odd. I actually pulled over and checked everything because it was so unusual.

I also tried different grades of fuel. What I found surprising was that my fuel mileage dropped noticeably when using premium (91 or 93). The mpg was best with 87 or 89 but I only put in 87 if the day's was going to be relatively flat. I didn't use 85 octane and was surprised that you could buy it.

Eisenhower Pass (and one other that I can't remember) slowed the truck down the most. The last mile or so was at 28 mph. I had the throttle buried and if I had 4.30's, I probably could have gone a little faster but not enough to make a difference at the end of the day. What I did notice was that the transmission probably has some kind of electronic protection. On three separate occasions, the engine would be pulling strong in 2nd gear (steep grade) and running at 2800 rpm. Even though there was no rise in temperature (engine, transmission, water and/or oil), for no reason, it felt as if the converter would lock up, the rpms would immediately drop to 2200 and the truck's speed would fall off quickly. I'm positive this had something was to do with the computer.

Am I all for just gassers? No but I will admit that I was pleasantly surprised how well this one performed. Honestly, I didn't think it was going to perform that well with the 3.73's. But it performed well, especially considering it's mileage. I would have preferred being able to drive a little further on a tank but there's not much I can do to improve it (unless, I get a different truck).

This truck works fine and I have no reason to get a new one. It'll be paid for in a few months and still runs great. Does that mean I wouldn't get a diesel? No. My wife and I have been casually looking at used trucks and if we bought one in the next year or two, it would probably be a diesel. But, if we replaced the one we have, it wouldn't be purely based on the engine. It would be nice to have one with a newer transmission (dorkshift), a higher GVWR and a long bed (she originally bought the truck for herself - I inherited it when I bought her a new "truck"). The used price of the diesels are currently low enough to make them attractive. One benefit if we had one would be fewer gas stops, I'd probably drive faster and average a higher speed. Subsequently, the driving time (point A to B) would decrease or I'd cover more ground in one day just to get to our climbing locations (mountain climbing with our hands and feet). Would the added speed be measurable over a few miles. No. Over a few days, yes but still not enough to argue about it. I could care less if someone can pass me up a hill and if they cross over it a few seconds or minutes ahead of me, let them. Some people have different priorities. My wife has a great figure and cooks awesome chocolate chip cookies. Others like to brag about how fast they can drive a truck and trailer up a hill.

Just like many other over-hyped issues on the internet, I bet if I owned a truck with a diesel, there would be benefits, but the would probably be enough downsides for me to say "what's the big deal - in the big picture, it's not much different". It's still just a truck.