i got back into a ram yesterday (09 hemi rcsb 4x4) and though i am getting decent mileage, the fuel saver light only comes on if you're driving 50 mph. i was driving 55 or 60 and it wouldn't come on. my 07 that i had came on till 70 or so. anyone know what i can check into to get it working? thanks

 

Probably no issue here. I sometimes can get it at 55-60, but there are other factors here, mainly head or tail winds.

Could also be other factors compared to your old truck, such as different differential ratio. I have 3.92, which of course would make MDS at higher speed more difficult to achieve.

 

And what the gearing is on the truck. Mine will tend to be on at 65-70 on the freeway, But I've got the 3.21's

 

i'm doing 1700 at 60mph ,not sure what gears yet

 

the dealer had too much oil in it, i took out at least half a quart. will the wrong viscosity of oil cause the mds not to work? maybe the dealer put in 10w30 or something.

 

I have 3.92.

Yes, wrong oil will cause MDS issues. 5w-20 only.

 

i have to call the dealer tomorrow to see what he put in

 

Another reason to learn how to change your own oil, then you`ll know whats in it.
(3 dealers in my area ONLY use "bulk oil" = NO THANKS...!!!!!)
If your dealer changed it and installed 10w30, like others said in here, the MDS wont activate. (oil to heavy)
When equipped with MDS, never use anything heavier than 5w20. And if you want better MPG`s, switch to valvoline syn-power 5w20. (Hemi 7qts w/filter)

 

Seems unlikely that a Dodge dealer would put the wrong weight oil in. I run whatever 5w20 bulk oil it is the dealer puts in and somehow my truck survives

Just be aware that getting the MDS to stay on for long periods of time requires you to learn where the trucks happy spot is and how to use the throttle very gently once you are there.

 

y a i had an 07 and it worked to 70mph. the dealer said they put in 5-20 so i have to take it to dodge to diagnose.