Ok, I've been lurking about here, reading up on things, trying to grasp all the lingo like grape juice, white front vent caps for the front pumpkin using syn oil, etc for the past 6 months or so. Coming from 8 years with an Impala SS (that I too said I wouldn't mod--HA HA), I have found myself towing a 6300lb RV. The Impala SS (with mods) has all the power it needs to tow this RV, but it is not a great exp. The trailer has it by 1000lbs and in wind and hills....it isn't fun. Not towing, I eat most cars for lunch. :) Towing however is a whole different beast.

So, I now am able to afford a truck like the 2500HD Duramax. I've been reading all sorts of stuff about the 2nd gens and I am a bit concened about the fuel economy going so far south compared to the 1st gen Duramax. Also the heat issues I am reading about (from the varialbe turbo causing backpressure and the new EGR design and converter) concern me as well.

One of the main reasons I was considering the Duramax is that I approach things (as I've been told) with a Tim Allen type attitude. If it takes a inch, giver 'er 10 feet. I plan on towing in the mountains as a result of getting this truck and the diesel seemed like a great match. The fuel economy also came into the equation since the Duramax could get far better MPG than the 8.1L (at least when I started comparing the 1st gen to the 8.1L gasser). True a bad day with the Duramax regarding MPG with the LLY is equal to the 8.1L from some accounts, I was hoping for 15 towing. If I get some of the 8s and 9s I've been reading about, I could simply do the 8.1L w/ the 4l80e and be done with it. Please tell me it gets better (as I also have read the Duramax gets better with age).

So now here I am cash in hand, ready to take one with all these great GM rebates (making the once more expensive Duramax near the price of a gasser) and now I wonder if I should wait for 2005 or 2006 for the LLY to be refined a bit.

Please excuse some of my ignorance. My only diesel exp is with a Mercedes 300D (1982--a 5 banger turbo diesel) and except for that, I'm a gasser gear head, so a lot of this Duramax/Allison stuff will take me some time to adjust to.

Any input anyone might share would be greatly apprec.

Thanks,

EricEdited by: Silvertwinkie

My only issue and concern with my LLY is the fuel mileage. And it seems to be getting better.

I have an 02 GMC 2500HD with 290,000 miles on it. I use it to transport boats all over the country. She gets about 17 mpg with no load & 10.5 mpg with A load. But she is in the shop for the fifth time now for injectors & we dont know when she is coming back.http://www.dieselplace.com/forum/smileys/Ermm.gif





mine

My fuel economy with a similar load has been 11-12 mpg. Sure I would like to see better numbers, most likely won't. The numbers will not seem as bad when you feel the power the Duramax has when a load is hooked on it's rear. A 6300 lb RV will not even make a D/max break a sweat. In fact the truck will seem to pull better with a 10,000 lb load.

On my LLY, I get 13-14 mpg in the city and about 15-16 mpg on the highway. City/Highway driving will get me about 14-15 mpg. All miles are on flat terrain and unloaded. Heading for the mountains in a few weeks. Will check out the fuel mileage on the hills. But one thing is for sure, I will be climbing smoothly and at speed in the DMax while the rest of vehicles are getting bog down or wheezzing their way up the hill.http://www.dieselplace.com/forum/smileys/HiHi.gif

With my Duramax i see 13 to 14 towing my boat about 3500#s. I use to see 10-11 with the 6.0l HD truck i had. I love the fact that i can make Lake Sam Rayburn and back on 1 tank.


I live in Houston where it is flat and i seem to get very good mileage for my truck normallly right at 18.5 mpg unloaded. Add some hills and my gas mileage will start slipping.

If your not in a big hurry silvertwinkie, I would wait and at least take a look at the 2005. I see you live in cooler climates than nevada, but after having just experienced towing a 8000lbs trailer in 95+ weather, I was really kinda disappointed. The truck gets hot and you end up looking like your driving a '73 pinto. I also only get 12MPG around town, and 16 at best on Freeway. Towing i only got 9.5. I just got back from a 2500 mile vacation, and this too is my first diesel. Sorry, I was just not that impressed in warm weather. Edited by: Coyzter

Thanks for the info. I am actually gonna wait until winter to see what shakes out. Did you happen to notice that the press release by GM talked about new cooling in what I thought was the full size trucks? If so, it sounds like GM re-eng the cooling. Maybe not...won't know until someone actually gets one. Of course, I'm not sure what that will do for the '04 folks.

First of you have a 7000# truck with and average RV of say 8000# total of 15K. If you get 10 mpg thats a damn sight better than the 8.1 gas at 5or 6 mpg.


As for it getting hot, I guess it depends on what you call hot. 310 hp pulling 15K or more is not going to be cool. If the fan comes on themn it does that is what its suppose to do.


I have 6800 on my 04 and couldn't be happier. The worst tank I have ever got was 15 mpg going 80 mph through the mountains. Slow down to 70-72 and I am getting 19.5 mpg. City has never been less than 17 mpg.


Power takes fuel, and IMHO the ecomomy for what we have is better than any gas truck. All the Dmax owners I know love their truck and forums always bring out the worst cases.





Greg

Thanks for the info. I agree, that in most cases the forum can have mostly folks that are having problems. However, if you read the 2005 press release, my take on that is that GM has done some tweaking to the truck line. I read areas of improvement are cooling, fuel economy etc. Now I'm not saying they specifically are talking the LLY here, but until there are more answers once a few '05s start hitting the streets, it kind of hard to make a guess as to what they have done to the LLY, if anything to address some of the concerns that a fair number of folks have with the LLY.

I currently have a gasser car with a 4L60E and 3.73s. The cars GVWR is 5380 and my RV is 6300lbs gross. I am darn near full to the max on both, yet my car engine temps are about 190 degrees on the warmest day and my trans never gets warmer than 200 degrees...mostly sticks at 175 degrees. With a truck like the Duramax, I'd expect 15k GCWVR of the truck and RV to be a walk in the park. I've towed up some very steep hills...over a mile long and still the trans only hit 200 for a short burst and the engine barely hit 200 itself. BTW, I have a quite liberal right foot as well. I can't confirm what folks are saying, but at the same time I am not quick to discount that there could be a few issues out there with the new '04.5 LLYs that need some tweaking (air conditioning being another issue).

Speaking of mileage, pick up a copy of this months Motor Trend. The have a three way towing test of the big three. Pretty interesting reading. Dodge last, GM second and Ford first. GM had the best mileage at about 18 and also the noisiest engine (?).

Traded a gorgeous 8.1 /Allison/ Jimmy for a Chev/LLY/allison. Every 2 weeks I drive the 1000+ miles from Wyoming to the great Northwest where I work. About half the time I pull an old 5th wheel trailer that weighs in at 8000#s.


I drive at the speed limit plus 5 (80 in WY,UT,ID, 70 in OR), pull hills floored, and just generally forget the trailer is there. http://dieselplace.com/forum/smileys/Evil%20Smile.gif


OK, here's my take on the gas vs. diesel thing. Without the trailer I like the gas. With the trailer I love the diesel. Stock with 3.73 gears and the gas on the floor both trucks will top a hill at the same time below about 3000'. Above that the turbo on the diesel really comes into its own, while the gas truck is forced to downshift and get very busy at 4400 rpm. During the 65k I owned it, the 8.1 averaged 11mpg around town 13.5 on the road empty, a hare over 8 pulling the trailer. Almost 10k on the LLY and I'm getting 11 pulling and 18 empty. I don't pay as much attention to in town because it just never gets alarming.


Your experiences may vary. For instance if I slow the trailer to 65 from 80 I see over 2mpg mileage improvement ( along with a 30% souring of my disposition) whether pulling or empty. The 8.1 showed smaller improvements. My friends in the East all seem to do a little better (lower altitudes, speed limits and a lack of 3 mile 6% grades to pull).


I proved to myself over the weekend that the fun factor can go way up on the diesel with just a $750 investment in a tuning box. 2.5 second improvement 0-60. How much would it cost to do that with your LT1? Of course, now I need exhaust, propane, transmission upgrades, etc. etc. Some of the rigs on this forum run in the 13s at 7200+ pounds. Tell Arizona Speed and Marine you want to do that with an 8.1 and they'll put a new wing on their building!


By the way I drive a brand new loaded 4 door 3/4 ton Dodge with a Cummins and 6 speed as a company truck. While it's the truck that convinced me it might be time for a dang smelly diesel, I'm always glad to get back in my Chev at the end of my 2 weeks on the job.


Good luck

Suffice to say GM, Ford and Dodge all have their +-'s. I've only had my D/A for about 2 months, and what a fun, powerful truck to drive. I'm certain Ford and Dodge owners would say the same. My fuel mileage averages 15-16 mpg around town and 18-19 mpg on the road. Towing a 40' Sunnybrook toy hauler the mileage drops considerably (9-11), especially in traffic or long/steep grades. Your wanting 15 towing? Good luck! Maybe on a 10 mile downhill with a stiff breeze behind you, no bumps in the road, low humidity, ... You will find that there are numerous variables that affect towing MPG's, i.e. tire size; load; frontal mass; tire pressure; wind; driving habits (leadfoot?); etc. No surprise to me to see the low mpg's with trucks running larger diameter tires(physics). When I drive I tend to stay around 70mph, the wife is more comfortable at 60mph. Guess who gets better mileage, yeah the sweet thang! I saw a post recently where someone read on the GM site there were numerous changes to the 05 2500/3500's, only to find out most of them only applied to the 1500. If you are going to tow make sure you stay within the GCWR, GVWR and GAWR ratings. Salesmen will proclaim their vehicle will tow anything, don't trust them. Each manufacturer posts their specifications for loads, weights, towing, etc. Happy shopping!