Diesel Oil Change Frequency

[Kanusport]

I like to change diesel oil every day, in other people’s rigs and equipment.


As the owner of an oil change business I’d stay up on the fuel filters and oil changes those items are cheap. Mechanics are not. Lots of good info here in this thread. I suggest 5000 miles on a diesel oil change and I use a product similar to rotella for installers like myself. Some rigs can and do go much further. Many of my clients go up to 12000 but some do as little as 3000. Most important thing is to change the oil and fuel filters.

[guskmg]

Originally Posted by tjdonahoe

When the particulate filter is in burn mode the fuel is injected into the muffler for the burn...not extra fuel into the cylinders...don’t be idleing....that is the major cause of fuel in the oil

That was not the case for 2007.5 to 2011 engines. These engines use direct engine injection to fire the burn off. They were forbidden to use any biodiesel over 5% because the unburned bio would go pass the rings into the crankcase and if not checked would cause crankshaft hydraulic lock up. Because 20% bio in the standard truck stop fuel, the 5% bio users are forced to convert their trucks to off road use only. That is, delete the soot filter (DPF) and the programmed direct injection for burn off. GM guidance was issued in order for these trucks to operate with bio 20 or bio100.
guskmg

[switz]

Mercedes publicly stated for our 2007 ML 320 CDI and 2009 E320 Bluetooth (the later is a regeneration car pre DEF fluid) 3.0L V6 diesels, that over 5% bio-diesel use would void the engine warranty. And we were told to avoid bio-diesel if at all possible. That was also the mantra of the service department for longevity of the engine.

My 2012 Ram 6.7 Cummins has the 5% maximum bio-diesel restriction also plainly stated in the owners manuals. Thus we never ever use the big three truck stops that proclaim up to 20% bio-diesel on their pumps both in back for the big rigs and out front.

[Scott59]

I have a 2016 Duramax 6.6l diesel and I change the oil at 6-7,500 miles. It's also important to change your fuel filter every 22,000 miles or so.

[wulfraat]

Computer on my 2017 duramax had me change fuel filter at 15k miles.

[jcl]

It is difficult to directly compare change frequencies without considering the factors that shift the numbers up or down without adding or subtracting any risk.

A larger oil sump results in a longer oil change interval, all other things being equal. It was the only way that the diesel engine manufacturer I worked with supported increasing oil change intervals at the time. Put on a sump with double the capacity, and it doubled the interval. We sold diesels with up to three sump sizes. Using hours or miles as an interval without qualifying these sorts of factors can lead to incorrect comparisons.


My 3.0 litre gasoline engine goes 24,000 km between changes, and up to 28,000 km per the on board computer. At the same time, it has a 9 litre oil sump, pretty large compared to similar engines.

[akflyer]

To specifically answer the OP's question about the oil change time limitation (vs the mileage), my understanding is that it's a recommendation based on increasing acidity of the engine oil over time. As others have pointed out, the oil doesn't "break down" during that short period, but it does become become contaminated and more acidic over time from engine combustion product blow-by, oxygen, and water. All of those contribute to eventually causing corrosion in the engine.

If you send in samples for oil analysis, you can specifically request the TAN (Total Acidity Number) test, but it usually costs extra.

Most people probably don't care too much about long term corrosion in their engine because they'll probably sell it and move on way before it becomes a problem. I figure on my Dodge 2500 the electrical system will kick the bucket way before the Cummins gives out, regardless of how often I change oil. I change my truck oil every 12 months regardless of mileage.

In the world of small airplanes, it's normal to change engine oil every 4 months regardless of useage because (a) small aircraft engines typically get more blow-by than a modern car engine, and hence more contaminants (b) the engine is expected to last much longer, and (c) the cost of the engine alone on my small plane is more than the cost of what I paid for my truck. So yeah, I follow the 4 month rule pretty religiously on that.

[jcl]

Agree with point about acids collecting in the oil as it sits, that is part of the time limitation.

Recognize that while oil never stops being slippery (it fact it lubricates better with some miles on it than when new, according to many studies) it gets contaminated (so pay attention to the filter) and the additive package loses effectiveness. The state of the additives can be determined with TBN (total base number) analysis as part of the oil sample. Many modern engines have an oil sensor that uses capacitance to estimate the depletion of the additives, and adds that in to the engine computer algorithm that says when to change the oil. That often confuses people who think that their engine computer is measure time and miles, and total fuel burned, but don't consider that the oil quality is also being monitored.

[vintageracer]

The second issue that's just as important as the diesel oil and filter change and in my view MORE IMPORTANT is changing your DIESEL FUEL FILTER every time your change your diesel oil and filter.

It's good practice is to change your fuel filter every time your change your oil filter. If you are running your diesel 15K miles between oil/filter changes you should do 2 fuel filter changes during that time. 1 @ 7500 miles and the second at oil/filter change time given what can be the poor quality of diesel fuel at some stations. Your EXPENSIVE high pressure fuel injectors will thank you!

The only way old oil will stop your diesel engine while driving down the road within reason is a hole in the oil pan! Meaning NO OIL in the engine! A bad fuel filter will shut down that diesel engine right quick at the worst time when you are traveling! I suggest everyone always carry a replacement fuel filter in their diesel truck for just such an occasion.

I change my diesel oil/filter every 7500 miles on all my diesel trucks AND the fuel filter at the same time every time. I suggest you do the same!

[KWN306]

Originally Posted by EarlM

I change when the indicator says to.

the comment oil stabilizers break down, is false, do you think the oil you buy was just made yesterday. if it doesn't breakdown in the container why would it breakdown in the oil pan?????

This is the most ignorant statement that I have ever read. Heat and cooling cycles and carbon break down oil. If the vehicles only purpose it just to pull a trailer then it sits and you have condensation form in the oil (unless you are a full timer.) Last time I checked water doesn't lubricate bearings in a diesel motor or a gas motor very well.

[cliffcharb]

There is no fast and true magic number, it’s all dependent on use, conditions and load. I work for one of the largest waste haulers in the country and each piece of equipment is different. Large trucks intervals were doubled years ago with no adverse affects. Oil analysis is completed 3 times between oil/filter changes to confirm. Our smaller trucks, 350’s - 550’s are changed at roughly 5000 miles and heavy equipment is around 250 hours. Fuel filters are always changed at the same time.
Personal vehicle ranged from 10k - 15k depending on what it’s been towing.

[Alu27]

Hans627,

Owing a cummins diesel was the logical choice. I own a 2014 6.7 myself, with over 125K miles, pulling a 27' Classic. This is my forth diesel, owning three Navistars in the past. Which, for this conversation, means zippo.

All of the Forum input for you is good, except, other mfgr engines have different maint requirements.

My input, stick with what Ram/Cummins tells you. 15K maintenance works. As one member wrote, you can have your oil tested. I did, twice. Again, with the cummins, oil changes every 15K is fine.

Remember, the 95/100 pickups that deliver campers out of Elkhart drive Ram cummins pickups.

[perryg114]

I know this is heresy but I change the oil in my Kutoba tractor every 100 hrs no matter how many years it takes. Runs like new. Blackstone labs will tell all.



Perry

[fastrob]

Suggest Ram Cummins Forum. https://www.cumminsforum.com/forum/
Select your Generation truck and join in.
Some commercial drivers go 50-100,000 miles on their oil. Oil testing, bypass filtration and filter only changes are some of the techniques used to get long oil life.
I do twice a year oil and filter about every 7500 miles only because I basically use the truck twice a year.
If you are not expecting a million miles, your money, your ride, do it your way.

[tjdonahoe]

Originally Posted by vintageracer

The second issue that's just as important as the diesel oil and filter change and in my view MORE IMPORTANT is changing your DIESEL FUEL FILTER every time your change your diesel oil and filter.

It's good practice is to change your fuel filter every time your change your oil filter. If you are running your diesel 15K miles between oil/filter changes you should do 2 fuel filter changes during that time. 1 @ 7500 miles and the second at oil/filter change time given what can be the poor quality of diesel fuel at some stations. Your EXPENSIVE high pressure fuel injectors will thank you!

The only way old oil will stop your diesel engine while driving down the road within reason is a hole in the oil pan! Meaning NO OIL in the engine! A bad fuel filter will shut down that diesel engine right quick at the worst time when you are traveling! I suggest everyone always carry a replacement fuel filter in their diesel truck for just such an occasion.

I change my diesel oil/filter every 7500 miles on all my diesel trucks AND the fuel filter at the same time every time. I suggest you do the same!

I buy my fuel wherever they sell a lot of fuel....on my cat engine..40,000 miles...fuel filter gets changed..never had a problem and it now has 1.4 million miles with the original injectors..my new ram says 15,000 miles...25,000 in my opinion is plenty as there 2 filters...

[broupman]

Originally Posted by perryg114

Rotella-T6. I would change and sample at 7500 miles and send the sample to Blackstone Labs for an oil analysis. They can tell you if the oil is worn out. I would not change oil more than once a year unless it is for mileage. As much as these things cost, don't run cheap mineral oil in them. You can probably go at least 10k between changes without an issue. Synthetics are better when you dump the oil than mineral oil is new. We tested this stuff at NASA and it is a lot better than mineral oil.



Perry

Agreed, far to many debates on what people or dealerships think should be done. Send samples to a lab and have chemistry tell you when to change oil. Just make sure you purchase a high quality oil filter, because you’ll probably be surprised at how long you can run modern oil or synthetics. Warranty claims is also another great reason to send samples to the lab on a set interval. Hard for a manufacture to argue with an analysis if there has been a steady increase in wear metals in the oil, and you’ve been following their maintenance schedule.

[Scoutx]

Originally Posted by Hans627

I am driving my first diesel, a 6.7 Cummins. The recommended oil change is 6 months or 15,000 miles. The truck has an oil change indicator.

My question is why is it important to change the oil at the 6 month intervals? Especially if the oil change indicator says there is no need to change the oil and the 15,000 threshold has not been reached.

For those of you towing with a diesel do you change your oil every 6 months?

Thanks!

The ideal solution would be to take an oil sample after 6 months if typical driving and send it out for analysis ($25). Once you find out what's actually taking place you can decide whether the 6 month interval is actually relevant to you needs. Likewisr I would take another at 15k and if there are no issues then that service interval is suitable. If not shorten up your interval. A lot is going to depend on the type of oil you're using. Straight Dino or blend and your service intervals may be shorter. Full synthetic and you can probably do 15k.
VW specs a 10k interval for their diesels and testing shows that under typical driving even that is conservative. But then they spec only full synthetics to be used.

[Alan 117]

Originally Posted by sbowman

Every 5k Rotella T-6 5W-40


Safe travels and best regards

You are a legend.
Best oil and interval. Why?
Definitely fantastic oil.
It's possible to do damage to your engine with change intervals that are too long or mileage that is too high but you can't hurt anything by doing oil changes too often.
Compared to a $20,000 engine change what''s an oil change. Just for reference semi drivers run synthetic and change every 10,000 miles on average from what I've read. If I were driving 10,000 miles a month I might go 10,000 but driving 15,000 a year, 5,000 mile intervals make sense to me especially since the government has the modern diesels eating their own exhaust.

[SimRunner]

I have a 2017 F250 diesel with no modifications. Running Shell T6 SAE 5W-40 Synthetic Extreme Temperature Triple Protection Plus Heavy-Duty Diesel Engine Oil. Here’s a point of reference.

Sent sample from last oil change to Blackstone Labs. The oil and oil filter had 7,126 miles of use over three months…about half of the miles were towing. The truck was not indicating the need for an oil change.

Blackstone reported that the oil test reading “looks great.” They recommended trying 9,000 miles for the next sample. I will likely change the oil and filter between 5,000 and 7,500 miles, unless the oil change indicator displays a message sooner.

[jcl]

Despite the name oil sampling, oil sampling isn’t primarily intended to see how your oil is doing. It is to see and then trend engine wear rates over a longer term, eg many oil changes, so as to catch issues before failure, those typically being cheaper to repair than after failure.

Most oil sample tests focus on measuring metals. That doesn’t tell you about the oil, despite what some labs say.

If you want to track your oil performance you need more than a test for wear metals. Pay extra for the TAN/TBN test, and consider doing large particle analysis if you are looking at a specific component.

One or two tests tell you very little. Start with a clean oil sample test to establish a baseline. Then do sampling every 500 hours or so and track and graph the results. When the wear rate line kicks up, that can indicate where you should be changing oil.

If you want to do one test to see what it shows, that’s fine, but don’t base any changes in service intervals on it.

Despite having worked a short spell in my employer’s SOS lab (Cat dealer) and having access to it for my own vehicles, I have never sampled my own vehicle. It simply doesn’t offer a payback. But it can be interesting to do one sample to see what it is all about. Just don’t take those results as a guide for oil change intervals.