Originally Posted by im6under

this looks like a good place to jump in...

I was at the dealership a few days ago and really found out nothing...

silly dealer wanted to sell a truck and not impart info...

to me... the mercedes get the very best mileage (period) nice broad torque curve for everything but colorado.

how long do they last? I wish I knew... can they be rebuilt??? I wish I knew... why do they need to be rebuilt??? I wish I knew....

all the dealer could tell me was they had a bad rap at the start for a plastic freeze plug that leaked and a bunch of guys overheated and junked the motors... prior to the recall...

??????b.s. ?????? I wish I knew... lol


anybody know the particulars???



and on the topic of fuel mileage....

whats the difference between a 10 and a 13 speed. no not three gears... i know that much... how much will it kill the MPG????

dealer said, not much... maybe a tenth is all.

I said I heard almost one MPG lost going to a 13 speed.

he said that's b.s. nobody has done any studies on the differences to back that up at all !!!!!!!!

so I asked... then how do you know its only a tenth at most???????

conversation over as he handed me an application for credit I didn't want...

parting words... " it's all in the gearing"

yeah??? what gear do I need????

"I dunno, we'll take you out on the lot and let you test drive a few or all of them til you find one that will work the best for you..."


oh K ! and alrighty then... I'll stop back by when I have more time...

like the second tuesday of the third week of the month.... hehehe...

Originally Posted by BobC

I pulled food grade tanker.
I was either at 80k or empty at 30k.
Running mostly from Fl to Cali on I10 & back out on I40 or I80.

Loaded, I never had a cat that got decent fuel mileage. (4.75-5.25)
Under similar conditions, Detroits gave much better mileage (6+).
Both types of trucks had super tens.
I doubt the rears were the same & cannot recall what each were.

The caveats to my empirical measurements.
The cats were cut back from factory. (475 down to who knows?)
The Detroits were set for factory.
The cats were in T2k's while the Detroits were in T600/T800's.

My overall opinion is that ther bigger motors will generally give the better overall mpg.
A few OO's having 550 cats told me they got an average of 5.5 or slightly better running a lot heavier than me.

When I ran for a food grade joint that ran all Mack E427's, the factory settings gave me the best mpg.
After the garage turned them down, they couldn't pull themselves off a cliff & my mpg dropped from what was close to 7 mpg to barely over 5mpg. Some savings eh?

I tried driving the "cut back" truck differently to improve the mpg's.
Nothing I did including long stints at 55-60mph made any meaningful improvements.

I "got around" the computer & my mpg went right back up to where it was initially.

Originally Posted by im6under

this looks like a good place to jump in...

I was at the dealership a few days ago and really found out nothing...

silly dealer wanted to sell a truck and not impart info...

to me... the mercedes get the very best mileage (period) nice broad torque curve for everything but colorado.

how long do they last? I wish I knew... can they be rebuilt??? I wish I knew... why do they need to be rebuilt??? I wish I knew....

all the dealer could tell me was they had a bad rap at the start for a plastic freeze plug that leaked and a bunch of guys overheated and junked the motors... prior to the recall...

??????b.s. ?????? I wish I knew... lol


anybody know the particulars???



and on the topic of fuel mileage....

whats the difference between a 10 and a 13 speed. no not three gears... i know that much... how much will it kill the MPG????

dealer said, not much... maybe a tenth is all.

I said I heard almost one MPG lost going to a 13 speed.

he said that's b.s. nobody has done any studies on the differences to back that up at all !!!!!!!!

so I asked... then how do you know its only a tenth at most???????

conversation over as he handed me an application for credit I didn't want...

parting words... " it's all in the gearing"

yeah??? what gear do I need????

"I dunno, we'll take you out on the lot and let you test drive a few or all of them til you find one that will work the best for you..."


oh K ! and alrighty then... I'll stop back by when I have more time...

like the second tuesday of the third week of the month.... hehehe...

Originally Posted by Brickman

I aint buying a 13 gets worse MPGs. With a 10 your RPM jump is so big between each gear you are either wrapping the engine out or lugging it down. With a 13 you have about a 300 to 400 RPM jump. MUCH easier to keep that in the sweet spot of the engine.

Also the Mercedes have a bad rap for several reasons. Parts availability, parts price, qualified shops to work on them do not abound across the country like if you have a Kitty, cumapart, or a driptroit.





CATs can get good MPGs, its all in how they are set up and driven.

Originally Posted by 2fuzy

A 13 will cost you nothing and most have a 27% overdrive compared a 15% in most 10s

Originally Posted by kotflb

BOBC. I "got around" the computer & my mpg went right back up to where it was initially.

please tell me how you "got around' the computer. I've spent big $$$$$ on this '99 Mack, 460, trying to get the mileage up, and so far nothing has worked. I can't hardly get 6mpg lightly loaded and when grossed near 80k, I have to really baby it to get 5 mpg. I 've even thought about slipping a S60 dd under the hood of this dog. Whats your secret. I know its got to be that computer holding me back mileage wise, Fine truck otherwise.

Originally Posted by 5mouths2feed

I am going to have to disagree with you here.

Whether it is a 9od,10od, 13 DBl od or an 18 dbl od they have the same final drive or almost.... All 97-08 Eatons are either .73 or .74
Meritors are a little different they have 4 numbers .72, .74, .80 and .87

The difference with both the 13 and 18 Eaton is the ability to run between the gears offered in the 9 or 10 od.

Overall given the same driver, truck, terrain, engine and rear-end gears I would have to say that more gears may tend to give better milage by being able to best match rpms to terrain and load.

In the case of Meritor the 10od should do better with milage since their 13spd has that outta nowhere .87??WTF?? and their 16spd??WTF?? has a .83 final VS .73 in the 10od.

If anyone is interested in the exact ratio for each gear for tranny's PM me and I'll give you the site. Got in trouble offering this help before so I am not posting the name again.