I have a totally stock 2004 Dodge 3500 dually.
I was active on various Diesel forums when I first bought the truck new in 2004.
Various forum members recommended adding Power Service and Marvel Mystery oil to the fuel. Well I did for a while and then stopped. Lately, specifically with the low sulfer fuel, the engine is not as quiet as it used to be and the MPG has gone down. I currently have 41,000 miles on the truck. So, I started using the combination of Power Service and Marvel Mystery Oil again. This week I went to a conference about 120 miles each way. I filled the truck up before the trip and forgot to add the PS and MMO.
On the trip to the conference the mileage display (my display has been very accurate, maybe because the truck is stock) showed an average of 17.5 mpg and when I stopped to refuel myself at the Golden Arches the engine was very loud, sounded like it was knocking. After the conference, based on reading some posts to this forum, I picked up and added 16oz of 2cycle oil to the fuel. To my surprise, on the return trip I averaged 20.5 mpg and the engine was significantly quieter.
With that increase in mileage, the cost of the oil insignificant compared to the diesel fuel savings. There didn't seem to be any other significient difference in the trip, rolling hills both way.
I am curious to see if anyone else has noticed this kind of mpg difference and is the 2 cycle oil or the combination of PS and MMO better for the engine.

Thanks
DodgeBob

 

DodgeBob. Kick yo boots off and stay awhile. Make sure you go to the DB initiation thread and introduce yourself.


First off, stop putting MMO in your fuel. It has an additive package that does not completely burn and will over time cause problems with injectors and rings.
Yes, many studies have been done and its been proven that adding 2 stroke oil will improve mileage. Here's two threads you can read on the subject. Also find the attached PDF that shows the results of an independent study.

https://www.dieselbombers.com/altern...il-thread.html

https://www.dieselbombers.com/altern...ditives-3.html

 

I for one don't use MMO. Never have. It works ok on older Cummins (pre ISBE trucks) but I still don't use it. I do however use Howes or PS before a long trip or a little here and there every month or so. Most certainly not ever fill as I have noticed many tanks of decreased economy running short trips using those adds.

Now in so far as your truck and it's mileage the key is fuel pressure, fuel filttration and your personal effect on the skinny pedal. The configuration of the truck also plays into it IE 354 vs. 373 vs. 410 etc. Tire sizes, drive train choice and other things make a difference as well but all in all it comes down to what I've said above.

 

x2

 

Thanks for your advice, I appreciate the info. I will stick with the 2 cycle oil going forward.

Thanks Again

 

I'm another one that used to used that same mixture.
Iv got an 05 with 43000 on it and For about the last nine months, Iv been using strictly 2 stroke when fueling.
I put 1 oz per gallon and have noticed that the engine idles quieter with it.