Cummins oil change - synthetic?

Pnwfullsize

Active member
I have always used Valvoline royal blue with fleetguard filter every 5k. Not religiously so if it went over no big deal. I chose 5k simply because its an easy interval to remember and takes me about 6 months to get there. 2 oil changes a year. Swap the fuel filter with a new fleetguard every 10k. Extend the drain hose on the fuel filter housing to keep the draining process clean. Throw a fumoto valve on the oil pan.
 
D

Deleted member 12023

Guest
I have always used Valvoline royal blue with fleetguard filter every 5k. Not religiously so if it went over no big deal. I chose 5k simply because its an easy interval to remember and takes me about 6 months to get there. 2 oil changes a year. Swap the fuel filter with a new fleetguard every 10k. Extend the drain hose on the fuel filter housing to keep the draining process clean. Throw a fumoto valve on the oil pan.
Same here. Both Cummins trucks. Valvoline premium blue, fleet guard filters and 5k mile intervals. Easy to remember.
 
D

Deleted member 9101

Guest
The only way to actually tell what your oil change interval shoild be is through an oil analysis. Everything else is just a guess.

I'm willing to bet that fully synthetic oil at 10K will have plenty of life left in it.

If you are paranoid about going further, you can always change filter at 10k and top it off and run it for another 10k. I have done that in gas motora for years with no problems.
 
Last edited by a moderator:

luthj

Engineer In Residence
It would be rare for an IC engine to get hot enough to coke oil (even regular SN/API service). It can get hot enough to cause some sludge formation, which typically requires a better quality oil. So follow the MFG recommendation. The thermal stability of oils in general has improved as vehicle performance has. The big jump in HP since the 90s has pretty much required it. Given that you can get a good synthetic for less than 5$ a quart, its not really an issue.

Obviously it depends on the engine, but a rough estimate of the minimum oil life is 4000 mile-liters per quart of oil (mile-liters/quart). So if you have a 7 liter engine with a 9 quart oil capacity. This would be severe service, not highway cruising. My turbo diesel is sub 3 liters with an 8 quart capacity. Testing shows oil is great at 10k miles, and I could easily push that into the low teens.

(9 quarts/7 liters)x4000 = 5142 miles.
 

plumber mike

Adventurer
Synthetic for myself in both the Cummins. Smoother sounding cold starts. Fumoto valve is nice but the filter still is a mess on a 4th Gen. Observing proper EGT cool down before shutting off the truck seems to go a long way towards preventing oil breakdown. I don’t think the engine itself has the heat to coke, but the turbo temps sure do.
 

surfram

New member
Conventional 15-40 every 5k. Pick any major name brand diesel oil. Did this in my 2004 Cummins for 15 years and 200k. Doing the same with my 2018.
 

tatanka48

Active member
my mechanic turned me onto Royal Purple full synthetic many moons ago when he was running it in his Dodge/Cummings

(he does say he is confident the Rotela and Delo full synthetics are just as good ±)

the engine tranny both diffs and transfer case are all filled w/ the full synthetic Purple stuff

i have a 2002 F-350 7.3 SRW 4x4 that has over 365k on it and the only failures have been common wear external components(cooling system starter injectors...) NOT the engine itself

i did have the tranny rebuilt @ just under 200k(something about HEAVY pulling in reverse) butt the engine transfer case and both diffs are still stock original components

i am on a 10k interval where @ the 1st 10k i just change the filter/top off and @ the 2nd 10k i do a full oil n filter change

that means that 11qts go the full 20k

as for duty the last time i ran across a scale it weighed over 27k# hauling an antique firetruck on a trailer from Little Rock to DFW

fullsizeoutput_1345.jpeg

the heat where i am is usually considered severe duty unto itself

when it comes to mileage/fluid changes everyone has their own personal feelings and i am only sharing my personal experience w/ full synthetic fluids in a diesel powered 1-ton truck that has earned it's stripes

in the event this truck does need replacing or i win the lottery and just want a new one i'll do with it as i have with this one

"T"
 
Top