20 Mpg!
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
Originally Posted by Pete in Maine
Is it cost effective to switch to 3:55? What does that mean for my low end? Empty, I typically start out in 2nd gear because first is so low. If it isn't obvious, my knowledge of things automotive is pretty limited.
Suber, I have been doing just that. Baught the truck to pull my boat, but suspect I'll end up under the truck more than on the water thanks to all the FTE info I'm gathering.
Suber, I have been doing just that. Baught the truck to pull my boat, but suspect I'll end up under the truck more than on the water thanks to all the FTE info I'm gathering.
The to answer your question about the cost effectiveness of switching gears. No its not cost effective. Both the truck I have now and my previous PSD were 3.55's and they get no better mileage than many of the numbers stated here. with the 95 ex-cab 4wd I had a best of 19.5 that was 55mph for 4 hours straight with an average of 15-17 but mostly 15.5 to 16 mpg. With the truck in my sig I get 15 average. I drive like a race car up to 65 mph and stay there usually. both trucks are 4wd with 285/75R16 tires with average thread type. so it would not pay to drop 1000-1500 for a gear swap cause your mileage might actually go down.
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Elder User
Joined: May 2007
Posts: 999
Likes: 0
Originally Posted by bkcowboss
tn, I am still intrigued as to the performance of the marvel mystery oil, I have been putting 2 stroke oil in my fuel and saw a .5 mpg increase in my average, (and I watch religiously) I have often considered dropping the MMO in to see how it did. When you started running it could you tell a difference?
Lead Driver
Joined: Aug 2006
Posts: 5,259
Likes: 17
From: Gambrills
Originally Posted by BadDogPSD
Hi Pete and welcome to FTE!
Check your door sticker. Your axle code should be listed. I think I have this right:
3:55 Open is code 39
3:55 Limited Slip is code C9
4:10 Open is 35
4:10 Ltd is C5
Best way to max your mpg is to make sure you have clean fuel filter, clean oil, and go easy on the accelerator. Most of us find the best MPG if we keep the rpm's below 2000.
As far as you mods go, why don't you start another thread. You will likely get more responses that way.
Check your door sticker. Your axle code should be listed. I think I have this right:
3:55 Open is code 39
3:55 Limited Slip is code C9
4:10 Open is 35
4:10 Ltd is C5
Best way to max your mpg is to make sure you have clean fuel filter, clean oil, and go easy on the accelerator. Most of us find the best MPG if we keep the rpm's below 2000.
As far as you mods go, why don't you start another thread. You will likely get more responses that way.
1 question though, What is the difference between the limited slip and open rear?
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
Limited slip will drive both wheel equally if its working correctly, open is a one wheel wonder. meaning if you are in snow, gravel, wet road only one wheel will spin. but in a properly functioning limited slip both wheel will spin but when going around corner the Limited slip will allow one the slip accounting to the different speeds the rear wheel are spinning on turns.
Posting Guru
Joined: Nov 2006
Posts: 1,059
Likes: 0
From: Herndon KY
Originally Posted by tndiesel
As I've said, I drive her easy and and smooth around town. I feel like the MMO has helped about 2 extra MPG around town. Of course this is just my opinion and my easy driving might have everything to do with better MPG.
Senior User
Joined: Oct 2005
Posts: 149
Likes: 0
From: Northern Utah
Hi all, very interesting thread. I watch my mpg all the time and mine will stay 17-18 mpg on the hyway doing 70mph@2200rpm,(empty) if I go faster the mpg really suffers. That said I look at things a little different than most. I say my rig gets great mpg's because it's just shy of 7000 lb, seats six, 4:10 rears, and can tow/haul what ever i want when ever I want. in the good old days (before deisels where really available) to do all this required big cubic inches, and having ownded a 460 ford that would only get 8 mpg's on it's best day going down the hyway (60 mph) this is a dream. So if mpg's are the most important thing to you, and abillity as truely fexible vehicle (haul people, hosres, trailers, ect.) buy a geo.
Great thread.
Great thread.
Lead Driver
Joined: Aug 2006
Posts: 5,259
Likes: 17
From: Gambrills
Originally Posted by tjbeggs
Limited slip will drive both wheel equally if its working correctly, open is a one wheel wonder. meaning if you are in snow, gravel, wet road only one wheel will spin. but in a properly functioning limited slip both wheel will spin but when going around corner the Limited slip will allow one the slip accounting to the different speeds the rear wheel are spinning on turns.
Thanks TJ, so a limited slip is not to be confused with a Posi? Is the front axle Posi traction? Is that why on dry pavement it hops around a little when turning?
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
Techinically posi and limited slip aren't the same but they are the same in their outcome. the front diff is an open diff. it hops when the hubs are locked in on dry ground becuase there is an extreme speed difference for the front wheel when they are turning. much more than the rear.
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Fleet Mechanic
Joined: Mar 2007
Posts: 1,313
Likes: 6
From: Rio Rancho NM
I once got about 22mpg all the way from Flagstaff to Abq (300 mi). I had a 60mph tailwind for almost 250mi. Driving into that wind the previous day going TO Flag, I only got about 15mpg. I usually get 16/17 in town, 18/19 hiway empty.
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Elder User
Joined: May 2007
Posts: 999
Likes: 0
Originally Posted by bkcowboss
yeah I know what you meen there, that is the problem I have had with the 2 stroke oil, it took me a long time before I could say exactly what it was doing for me because my driving habits vary just a little bit. Thanks for the info, I may give it a shot, just need to do a cost analysis.
Posting Guru
Joined: Mar 2007
Posts: 1,842
Likes: 2
From: hillsborough nj
lol anyone wanna know how many miles i got out of my last tank?? (remember i just put in stage 2 injectors.... the fun hasn't stopped yet 
) i got 140 miles out of my last tank..... how pathetic is that lol that was running it down to right when it hit the red "zone" lol
) i got 140 miles out of my last tank..... how pathetic is that lol that was running it down to right when it hit the red "zone" lol
Posting Guru
Joined: Mar 2007
Posts: 1,842
Likes: 2
From: hillsborough nj
Originally Posted by tjbeggs
Limited slip will drive both wheel equally if its working correctly, open is a one wheel wonder. meaning if you are in snow, gravel, wet road only one wheel will spin. but in a properly functioning limited slip both wheel will spin but when going around corner the Limited slip will allow one the slip accounting to the different speeds the rear wheel are spinning on turns.
Elder User
Joined: Nov 2005
Posts: 555
Likes: 0
From: Cincinnati OH
wow, this thread took off. i get 16.5 in town. 17 highway, 18 if lucky. i would say i am a moderate driver, i punch it a lot but i am not the guy on the highway dropping into third every two minutes weaving through traffic. this is first time i ever heard those tanks were that big. always thought they both equalled around 25 gals. with either tank having an unequal share in the total. i do what cuda does, 200 mi. on the odo and i switch tanks or fill up. little more on road trips on the highway just because there are enough bathroom breaks anyway with the family. i am, however, not suprised at the true capacities of the tanks because on occasion during those mentioned road trips, i have not been paying attention and run 560 miles on a fill up because i missed the "last gas for a crapload of miles" sign. the needle for both tanks was what i thought pegged on empty and i was freakin out, but never a stutter in the engine.
question is, is the guage so far off that most of us never run our tanks that low or is it an issue with the tank/filler design that prevents us from completely filling the tanks?
question is, is the guage so far off that most of us never run our tanks that low or is it an issue with the tank/filler design that prevents us from completely filling the tanks?
Elder User
Joined: Mar 2007
Posts: 522
Likes: 0
From: Albuquerque
Originally Posted by utahcrew
Hi all, very interesting thread. I watch my mpg all the time and mine will stay 17-18 mpg on the hyway doing 70mph@2200rpm,(empty) if I go faster the mpg really suffers. That said I look at things a little different than most. I say my rig gets great mpg's because it's just shy of 7000 lb, seats six, 4:10 rears, and can tow/haul what ever i want when ever I want. in the good old days (before deisels where really available) to do all this required big cubic inches, and having ownded a 460 ford that would only get 8 mpg's on it's best day going down the hyway (60 mph) this is a dream. So if mpg's are the most important thing to you, and abillity as truely fexible vehicle (haul people, hosres, trailers, ect.) buy a geo.
Great thread.
Great thread.