chris21

The weight of the truck is included in the weight that is being moved. A 9k trailer more than doubles the weight that the drivetrain and brakes need to move and stop (7k+9k)>14k. And yes changing lanes with a 36' sail certainly is different than an empty truck. I don't think my math or reading comprehension are problematic on this one

That much weight is over double the empty truck. Sure the truck can handle it well, comfortably even, but it significantly increases braking distances regardless of trailer brakes and slows acceleration and adds significant surface area to a wind. "Not noticing it" is a huge exaggeration. I'm sure you feel it every time you stop, change lanes, accelerate or hit a bump.

The AI response here is contradicting itself... torque and traction are different, more torque does not mean more traction. Too much torque will break traction.

What is the weight rating on those tires? Seems like too low of pressure for that truck

With large equipment or deep mud it is more of a use the higher gear to avoid spinning tires, getting stuck because of spinning tires and doing damage to your machine. The idea is if you run out of torque before you spin tires you can still downshift for more torque. If you are just spinning your tires in the lowest available gear you are stuck and things break. Automatic transmissions, traction control and electronic transfer cases change the calculation a little as you the driver have less control over each piece.

How many running hours for those 600 miles? These emissions systems don't like idling.

Not sure, I've never a seen a poor quality def warning. The distance part of the warning you're getting makes me think your truck wants a forced regen and fresh def, the codes indicate the tank/heater is bad. What year is your truck? If it is under warranty just bring it to a dealer. If not I would try a def fluid swap before replacing the tank.

Try draining the def and relacing with new if it has been sitting for a long time. Def does go bad after a little while.

I bought an SLE last year after driving both and a couple different 1500's. The difference in options and comfort between the pro and SLE is significant. If they had an Elevation trim equivalent for the 2500 I probably would have gotten that. I think a 2500 gasser SLE or LT trim is the best truck you can get for the price right now. The power seats allow you to adjust the angle of the seat as well as up/down/forward/back/recline and lumbar. The heated seats and steering wheel are nice in the winter here, as is remote start. Carpet with the all weather floor mats are way nicer than vinyl floors and easier to clean. The digital dash has grown on me a bit, GM doesn't exactly have a great track record with the prolonged function of analog gauges, the dash cluster was the weakest point on the 99-06.5 trucks which were probably the best trucks they ever made. I like the bigger infotainment screen. I will say that I like GM's wider screen vs other brands that have taller screens.

I'm pretty sure it doesn't actually recalibrate the speedometer it just changes the wheel speed sensor inputs to the computer. The truck still thinks it has stock tires.

37's would probably fit with a 3" lift. GM only has two gear ratios for these trucks 3.73 for gas and 3.42 for diesel. And they can't be programmed for anything else at the moment. The rough country module just corrects the speedometer and odometer to adjust for tire size it's not a programming device. You haven't said if your truck is gas or diesel, but for a gas truck the 10L1000 with 3.73 gears has a lower final drive ratio than the 6L90 it replaced would if it were swapped to 4.10s. GM used the same 3.73 gearing in 6 speed gas trucks. I don't think you'll have any issue running 37's with the 10 speed other than the reduction in mpg and towing/weight capacity which is as much of a function of the lift as the tire size.

I didn't mean to seem dismissive of hurting mpg. Lifting the truck while still using stock tires would hurt mpg too, I was just saying that both engines have plenty of low end combined with a low first gear that drivability would be fine with stock gears. Towing with a significant lift sucks regardless of engine, transmission and gear ratios. And suspensions that allow extra travel don't carry extra weight well. If you're using the truck to tow or haul near capacity a big lift isn't great and reduces the the truck's capacity and these trucks are too heavy and long to be good for serious off road.

37's are within 10% of stock. The 10 speed has a really low 1st gear. Neither engine will really struggle. There is only one device currently that can trick the computer to correct for tire size, there are no programmers that work on the global B trucks that I am aware of, so programming the transmission shift points for re-gearing isn't possible at this time that is why there are no parts available for it.

Top yours off when you want. That is your decision. Different engines can have different markings and recomendations. The LT1 in my boat for instance the dipstick has 8 oz. Markings for a 1.5 qt range(7 dimples 1/4" apart) and 5qt sump it uses 20w-50 race oil and I keep it between the top two marks and change the oil every season or 50 running hrs. My truck has the 1 liter crosshatch and it depends on how soon I am going to be changing the oil how far down the crosshatch I would let it get before adding some. I haven't needed to add oil to my current truck as I haven't seen it below the top quarter of the crosshatch within 4000 mile oil changes. I had a 2002 5.3l that I added a full quart to every 2000-2500 miles that I drove until I sold it with 275,000 miles on it and a 4.8l that I never had to add oil to between changes that I drove until it had 300,000 miles. Every engine and use case is different. I'm sorry the owners manual is somewhat ambiguous I didn't write it.

You seem to be struggling with reading comprehension. I HAVE SAID 3 TIMES THAT THE BOTTOM OF THE CROSSHATCH IS A QUART OR LITER BELOW FULL. I have also said that the manual will not call that "1 quart low" because it is not a quart below the acceptable range in answer to asilverblazer saying that he has never seen the bottom of the marking noted as "1 quart low" in a manual. The wording of the manual allowing for an acceptable range would indicate that .00001" above the add mark is ok. Also, because the manual allows a range, a quart below full and a quart below acceptable are two different volumes. Thus the manual will not use the phrasing "1 quart low"