Dd15 maintenance questions

[JimT]

don't own one of those, but gear oil isn't recommended if the engine is burning oil and the DPF is intact as it will leave a lot of ash. Not sure the recommendation for engines with aftertreatment that don't burn oil.

Rawze's thread on gear lube:
Why I add 12% (one gallon) of gear lube at every oil change...

As for type and when to change oil, regular old conventional oil is the way to go, unless you're in an extreme cold weather application then synthetic will help with cold starts. As for brand, most guys recommend Rotella though any major name brand oil found at truck stops should be fine. Best to pick one and stick with it, which is why ease of availability is a factor.

Don't bother with oil or fuel additives unless you are treating a specific condition such as microbial growth in the fuel with a biocide. The so-called performance boosting additives rarely produce measurable benefits while costing a lot more then any maintenance they claim to prevent.

Oil change interval should be based on average fuel mileage during that oil's life.

ISX and Bypass Oil Filter Systems:

(03-01-2016 )Rawze Wrote:  Here is what I would recommend to others based on what I have seen..

If your average fuel mileage every 10,000 miles is ...

less than 5 MG -- Change your oil every 8,000 miles or so.

5 - 6 MPG -- Change your oil every 10,000 - 12,000 miles or so.

6 - 7 MPG -- Change your oil every 12,000 - 15,000 miles or so.

7 - 8 MPG -- Change your oil every 15,000 - 18,000 miles or so.

8 - 9 MPG -- Change your oil every 18,000 - 22,000 miles or so.

above 9 MPG -- Change your oil every 22,000 - 28,000 miles or so.

I did a little adjustment to the above numbers to come up with this simple calculation for my fuel mileage spreadsheet so I can easily track when my new oil change should be in real time with each fuel up:

Code:

Next Change = Previous change odometer + ((Average fuel mileage this oil - 2) * 3000)

For example:
Previous oil change: 586,296mi
Average Fuel Mileage since last oil change: 7.275mpg
586,296 + (( 7.275 -2) * 3000) = 602,120mi or about 15,824mi for that fuel mileage.

I use that calculation as a target for scheduling my next oil change. The above calculation changes Rawze's chart to look like this (Note that on the high and low ends of MPG my calculation is a bit conservative favoring slightly shorter intervals):

Code:

3 mpg --------> 3000 mi
4 mpg --------> 6000 mi
5 mpg --------> 9000 mi
6 mpg --------> 12,000 mi
7 mpg --------> 15,000 mi
8 mpg --------> 18,000 mi
9 mpg --------> 21,000 mi
10 mpg -------> 24,000 mi
11 mpg -------> 27,000 mi

values between intervals easily computed via simple equation:
( AVG MPG - 2 ) * 3000

For EGR enabled engines a bypass oil filter (an inexpensive Amsoil unit is typically recommended by people here) will greatly help reduce soot buildup in the oil but it shouldn't be used as a tool to extend oil drain intervals.

Personally I always change fuel filter with the oil. Fuel/water separator in mine is a Davco with the clear plastic housing so I change that according to it's level. If your freightliner has a different setup for fuel/water sep then you will need to follow different guidelines.

As for filter brands, I usually stick to the Fleetguard brand. Available almost everywhere and usually the most cost effective.

While the info on this site is geared toward Cummins engines the basic points of an EGR Tune-up are the same and will be one of the best tools to maximize engine and aftertreatment life and minimize down time.