Did you recently take on (or consider) a loan of 84 months or longer on a car purchase?
A reporter would like to speak with you about your experience; please reach out to PR@Edmunds.com by 7/25 for details.
A reporter would like to speak with you about your experience; please reach out to PR@Edmunds.com by 7/25 for details.
Options
Diesel vs. Gasoline
This discussion has been closed.
Comments
I suppose I should use Mopar filters and stuff, right? Is there any other brands that I could use? What about the oil, any special kind, or can I use good old Pennzoil? Any suggestions on buying in greater volumes than a case?
Any help would be appreciated. Thanks in advance
I know EXACTLY how you feel about towing with the Ram / Cummins / Auto combination. I have the exact same truck as you. Since you are running 2500rpms @ 60mph with OD off, I'm assuming you have the 3.54:1 ratio (same as me). If you had the 4.10:1 ratio, you would be taching @ 2775rpms.
I ran into this same problem the first time I went to tow my trailer. I wish I would have turned the O/D off when test driving the truck. I would NOT have bought it if I had!!! I feel this is a BIG problem with the Cummins/Auto configuration. This is probably why Dodge is looking at the 5-spd Allison Auto trans. There definitely needs to be another gear between 3rd and 4th(O/D).
My solution to the problem is I always tow with the O/D on! You will have to be careful not to let the trans "hunt" in and out of 3rd to prevent the fluid from overheating. I tow thru the mountains of KY which forces me to drive up and down a lot of hills (instead of very long drives uphill, then very long desents). You should be OK, but the Cummins does not pull heavy loads in O/D very well because of the high gearing.
The auto trans used was designed for a gas engine and not a diesel. Some people say... "So what!". But the problem arises because of the big differences in the way the two engines work. Diesel become very ineffient above a certain rpm range (around 2750 on the Cummins). With a diesel, the fuel continues to burn during the entire downward cycle of the piston and at some point the piston is moving faster than the burn rate of the fuel. Gas engines ignite the gasoline and causes a sudden explosion and the centrifical force of this forces the piston down the rest of the downward cycle. Thus, gas engines have a much higher rpm range than diesels because gas has a much higher burn rate than diesel fuel. But, that's why diesel have more torque, because the fuel is (usually) burning during the entire downward cycle instead of a sudden burn of the gas in gas engines.
My solution to the problem... I'm towing with O/D on and if the tranny blows, then Dodge will replace it! When Dodge comes out with a 5-spd auto, then I'm trading in the truck. If the warranty expires before this, then I'm selling it. Plain and simple!!!
I like EVERYTHING about the truck except the auto trans. That's why I'm getting rid of it after the warranty is gone.
I brought this very same subject up in the DODGE RAM II topic sometime in August. I wanted others to know about this BEFORE they bought one (Cummins/Auto). Following is a chart I found useful concerning tire size/ratio/gears/rpms. This is only for the Cummins w/Auto Trans...
3.54 axle
245/75 tires 265/75 tires
215/85 tires 235/85 tires
-------------------------------------------
(3rd/4th) (3rd/4th)
50mph 2000/1375rpm 1925/1325rpm
55mph 2200/1525rpm 2100/1450rpm
60mph 2400/1650rpm 2300/1575rpm
65mph 2600/1800rpm 2500/1725rpm
70mph 2800/1925rpm 2700/1850rpm
75mph 3000/2075rpm 2875/1975rpm
4.10 axle
245/75 tires 265/75 tires
215/85 tires 235/85 tires
-------------------------------------------
(3rd/4th) (3rd/4th)
50mph 2325/1600rpm 2225/1525rpm
55mph 2550/1750rpm 2450/1675rpm
60mph 2775/1925rpm 2675/1825rpm
65mph 3025/2075rpm 2900/1975rpm
70mph +red/2250rpm 3125/2125rpm
75mph +red/2400rpm +red/2300rpm
Good luck and make sure you take VERY good care of than tranny! Have it serviced every 9-10K miles!!!
Checker sells Valvoline Blue (aka Cummins Blue) for about $6 a gallon (my personal favorite). Walmart usually distributes Shell Rotella and their house brand of Diesel oil for about the same price.
I would personally only go 7500 miles if I were only doing long haul towing. For lots of short trips, I would half that distance between oil changes.
Thank you for the thorough explanation regarding the towing question for dodge diesel Automatic trans. You guessed right, I do have the 3:54 rear end ratio. Being that my 5th wheel is considerably less weight (8,000 lbs) than the trucks 9,700 lb tow rating, working the tranny in 4th may not be that difficult to handle. I tow 90% on flat ground here in central Canada.I did tow for seveal miles at 65 MPH overdrive on with no downshifting into 3rd what-so-ever. The tranny has an overheat warning light so I'll keep an eye on it. I also agree with your suggestion about frequent transmission servicing due to the extra strain the powererful cummins puts out. Do you suggest the usual transmission oil change or are there other adjustments to be made? Finally, the acceleration this truck puts out when towing is phenomenal compared to the 5.4 L Ford Triton I had previously. The rest of the truck is equally superior to the f250 as well
Stop worrying and start enjoying driving that magnificent machine. Just use a little common sense.
Mike
If you're mainly towing on flat terrain, then you'll be fine. Concerning the trans maintenance, I would just let a transmission shop to the work (e.g. change fluid and filter, adjust bands, etc.). Most sugest every 12K miles, but I'm planning on every 10K miles because I tow through mountanous terrain.
I'm just going on memory here, so I could be wrong. But isn't the tow rating for the Cummins/Auto 8400# and the Cummins/Manual 9700#? Anybody out there know for sure?
You shouldn't need any of these aftermarket transmission parts for your situation, but I'll include them for your future reference.
http://www.dieselpage.com/bdebd24.htm http://www.tstproducts.com
mharde2,
I agree that the transmission "should" be fine if you take care of it. But that's just my point... You have to baby it more than normal. Thus, if you agree that you have to keep a close eye on it's maintenance to keep it in proper working order, then it's safe to assume it's a definite weak link in the drive train! The biggest problem I have with the tranny is the gear spacing between 3rd & 4th. In 3rd @ 65mph you're running 2600rpm (and the pedals almost to the floor), but in 4th the rpms drop down to 1800. When towing in the hills, 3rd is too low and 4th is too high! Have you ever towed a 6-7K load with a Cummins auto? If you had, then I'm sure you'd know what I'm talking about.
If anyone is considering this combination (Cummins/Auto), definitely get the 4.10:1 axle ratio instead of the 3.54:1. This would raise your rpms a little (1800 up to 2075rpms @ 65mph) when towing in O/D and give you a little more power (and get more trans fluid flowing thru the transmission). I wish I had!
Brett
Here are the tow rating specs taken right out of the 99 Dodge Ram Brochure:
5.9 L Cummins A.T. 3.54 rear end ratio 9800 lbs
5.9 L Cummins A.T. 4.10 rear end ratio 11,800
I didn't realize there were so many after market performance enhancing products available for my truck. Thanks for sending the web sites!
Jack38.
I don't think you have to baby the auto trans just don't abuse it...Mike
Diesel vs Gasoline II.
Please continue there.
Front Porch Philosopher
SUV, Pickups, & Aftermarket and Accessories Host