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**Sandridge4** · 10-07-2022, 12:38 PM

Those are really good!! I have a 2020 F-350 CC DRW with the 6.7 and get 9.5-10.5 towing our 375RES average speed of 65mph and 16 without towing.

**FlyStar** · 10-07-2022, 03:38 PM

21 mpg but when towing, 10.5 mpg Duramax 2500 and 312 bhts TT

**Wileykid** · 10-08-2022, 07:06 AM

2019 RAM 3500 SRW 4x4 diesel with the HO, towing my 320G at just under 15K lbs, I get 10-11 mpg. Usually 15 mpg average not towing, 18-19 mpg on the highway at 65 mph or less. The HO cuts the mpg by 2-3 mpg over the standard diesel.

**Jlawles2** · 10-08-2022, 08:21 AM

2018 2500 Denali (4wd) pulling 303RLS I get between 8.5 and 10.5 depending on terrain. Unloaded I get 15.5-17.5 (I drive a lot of short trips with starts and stops when not towing). I did just clean the MAP / MAT sensor just downstream of the EGR, so hopefully that helps.

And it has about 97,000 miles on the clock.

**Guest** · 10-08-2022, 09:10 AM

Originally posted by Jlawles2 View Post

2018 2500 Denali (4wd) pulling 303RLS I get between 8.5 and 10.5 depending on terrain. Unloaded I get 15.5-17.5 (I drive a lot of short trips with starts and stops when not towing). I did just clean the MAP / MAT sensor just downstream of the EGR, so hopefully that helps.

And it has about 97,000 miles on the clock.

Joseph,

If your using an aftermarket filter that is oiled such as a K&N or other make, there are conditions where the oil can contaminate the down stream Sensors. Especially a MAF sensor...FYI

Jim

**Jlawles2** · 10-08-2022, 09:20 AM

Guest Jim, the 18 is bone stock except for the transmission thermostat delete (trusted Allison rebuilder that is no longer with us) due to the stop and go traffic I drive in allowing the trans to heat up quickly. It actually cost me nothing in economy to bypass the Trans T-stat.

I actually saw a post on a diesel forum where the MAP/MAT sensor gets build up from the EGR and PCV system. I do run full synthetic as I have had good luck with it on my 04, but since the API requirements have changed since the 04, it seems the newer oils tend to vaporize/atomize (this may not be the proper term for oil) and find their way into the intake.

See post 86 https://www.duramaxforum.com/threads...1013671/page-5 mine looked this bad.

**Guest** · 10-08-2022, 12:40 PM

Joseph,

Forums are great info but as we know many folks like to modify things whether it was a good idea or not, so I take things on auto forums with a grain of salt. Lots of amateur tuning on those sites. On a stock truck like yours with 96k miles, I would replace a sensor that is fouled. GM moved from a blended oil to a full synthetic 0w-20 on my little half ton. Like sewing machine oil. LOL

Jim

**Scott'n'Wendy** · 10-08-2022, 01:49 PM

I don't really relate 'fuel economy' with towing a trailer.......

**Jlawles2** · 10-08-2022, 01:54 PM

Guest Jim, I do take most of what they say with a grain of salt. The transmission thermostat bypass was something I came up with based on non towing temps being in the 180F range on open highway. With the bypass the temps stay below 165F on long runs without towing. My trans builder, where I ordered the bypass from, I consulted with before pulling the trigger. Also spoke with him about the new 10 speed (before he passed) and he said nothing but good things. Said the internals did pick up a few things from the 1/2 ton F150 and Camaro joint venture and that Allison did Certify the 10 speed after making changes. He also spoke about several other good things. He did have his hands on 2 un installed units for inspection about the same time they hit the market or just before.

As for the sensor, I chose to clean it b/c it's not the MAF (hot wires do not like cleaning) and most likely next time will consider replacing. I did notice a bit of performance change after I cleaned it.

**Calbar** · 10-08-2022, 05:06 PM

2022 Ram 3500 SRW 4x4 HO 6.7 and get 9.4 - 10.5 towing and 18-19 not towing nearly 16,000 lb Solitude in my signature. I only have about 4000 miles on the truck so no where near broken in yet. Hope it gets a bit better in a while but mileage is not what I bought the truck for.

Rob

**Country Campers** · 10-08-2022, 08:04 PM

10 - 11 towing, 3 going up hill 30 or more coasting down the other side, 18-20 empty driving, 100,000 miles and no real change in mileage. I would think it should be better than this but as others have said " I bought it for towing".

Brian

**Guest** · 10-08-2022, 08:34 PM

Originally posted by Jlawles2 View Post

Guest Jim, I do take most of what they say with a grain of salt. The transmission thermostat bypass was something I came up with based on non towing temps being in the 180F range on open highway. With the bypass the temps stay below 165F on long runs without towing. My trans builder, where I ordered the bypass from, I consulted with before pulling the trigger. Also spoke with him about the new 10 speed (before he passed) and he said nothing but good things. Said the internals did pick up a few things from the 1/2 ton F150 and Camaro joint venture and that Allison did Certify the 10 speed after making changes. He also spoke about several other good things. He did have his hands on 2 un installed units for inspection about the same time they hit the market or just before.

As for the sensor, I chose to clean it b/c it's not the MAF (hot wires do not like cleaning) and most likely next time will consider replacing. I did notice a bit of performance change after I cleaned it.

Can't compare with the engineers that designed the vehicle from the ground up. Not even remotely close. I do not expect folks to understand this but to be employed in the auto industry, only then can an individual gain an understanding in how much goes into these vehicles. Then the realization to leave it alone becomes clear.

Jim

**RoyB** · 10-10-2022, 07:50 AM

2021 Ram 3500 SRW 4x4 HO 6.7. Towing the 320G loaded (~17,5K lbs) I get around 9.5mpg @ 60-65mph. If I kick it up to 70-75 it drops significantly. 7-8. Depending on the situation and traffic...If I am just cruising I don't mind 65 mph. Less stressful and I am not trying to pass people all the time. If I am in traffic and want to get somewhere I am cruising at 75 and watching the gas gauge drop. This year with fuel @ $6/gal I have been driving slower everywhere.

For comparison I towed 2 ATVs on a single axle construction trailer (approx 4K total lbs) and a truck loaded to the gills for tent camping. Cruising 80-85 I was getting 12.5 mpg. On the way home I was cruising 75 and was 14.5. Empty at 70 I get around 18mpg. 20mpg at 65. These trucks get thirsty over 70 mph.

My '21 HO 8' bed weighs 9200 lbs with me and a full tank of fuel. My 2016 2500 Megacab weighed 8600 lb. That's a pretty substantial difference in vehicle weight too.

**Scott'n'Wendy** · 10-10-2022, 12:36 PM

Originally posted by RoyB View Post

2021 Ram 3500 SRW 4x4 HO 6.7. Towing the 320G loaded (~17,5K lbs) I get around 9.5mpg @ 60-65mph. If I kick it up to 70-75 it drops significantly. 7-8. Depending on the situation and traffic...If I am just cruising I don't mind 65 mph. Less stressful and I am not trying to pass people all the time.

I found with retirement I'm quite happy not going 70-75 to 'get there' anymore. And ya, we save fuel $$.

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