Anyone did switched to synthetic oil? I wonder if there is any bad effect to switching to synthetic oil on a 2003 Cummins. My engine book says we can do it.I would like to put 10W40 year long. It should be easier to start in colder temps and should last a year per oil change.Anyone using 5w40 synth. year long? This is what I use in my Ford Diesel.

Your eng should start easily down to -40 with grid heaters - about -30 without them so syn oil isn't really needed. You also have an eng that will go 700,000 to well over 1 million miles with normal maint. So it isn't really needed for longevity either.I tried in in two Cummins I owned but neither one got any better mileage or showed any kind of change. But if your the type that just likes to use the very best to take care of his toys (and I sure repect that!) then go for it. It sure wont hurt.

ScottG wrote:Your eng should start easily down to -40 with grid heaters - about -30 without them so syn oil isn't really needed. You also have an eng that will go 700,000 to well over 1 million miles with normal maint. So it isn't really needed for longevity either.I tried in in two Cummins I owned but neither one got any better mileage or showed any kind of change. But if your the type that just likes to use the very best to take care of his toys (and I sure repect that!) then go for it. It sure wont hurt.X2 (Couldn't have said it any better.)

The 10w40 synthetic rotella T6 here cost 104.00$ for 5 gallons, the 15W40 Diesel cost 83$. For the difference I would go for synthetic.But I never tried this engine in very cold weather with 15w40, I know my Ford needs the 0W40 to be sure it will start in the minus 30 temp.

Kidoo wrote:The 10w40 synthetic rotella T6 here cost 104.00$ for 5 gallons, the 15W40 Diesel cost 83$. For the difference I would go for synthetic.But I never tried this engine in very cold weather with 15w40, I know my Ford needs the 0W40 to be sure it will start in the minus 30 temp.Me too and I can go a year or more between 5000 mile changes so that's really not that much more money in the long run.

Synthetic Oil - Do you use it in Cummins Engine?

Sully2
Explorer
Oct 14, 2014
Do it....wont hurt a thing
Kidoo
Explorer
Oct 14, 2014
The 10w40 synthetic rotella T6 here cost 104.00$ for 5 gallons, the 15W40 Diesel cost 83$. For the difference I would go for synthetic.

But I never tried this engine in very cold weather with 15w40, I know my Ford needs the 0W40 to be sure it will start in the minus 30 temp.
Fishinghat
Explorer II
Oct 14, 2014
ScottG wrote:
Your eng should start easily down to -40 with grid heaters - about -30 without them so syn oil isn't really needed.
You also have an eng that will go 700,000 to well over 1 million miles with normal maint. So it isn't really needed for longevity either.
I tried in in two Cummins I owned but neither one got any better mileage or showed any kind of change.
But if your the type that just likes to use the very best to take care of his toys (and I sure repect that!) then go for it. It sure wont hurt.

X2 (Couldn't have said it any better.)
ScottG
Nomad
Oct 14, 2014
Your eng should start easily down to -40 with grid heaters - about -30 without them so syn oil isn't really needed.
You also have an eng that will go 700,000 to well over 1 million miles with normal maint. So it isn't really needed for longevity either.
I tried in in two Cummins I owned but neither one got any better mileage or showed any kind of change.
But if your the type that just likes to use the very best to take care of his toys (and I sure repect that!) then go for it. It sure wont hurt.

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Synthetic Oil - Do you use it in Cummins Engine?

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