I know the question will elicit various responses, but a post regarding a 2012 Ford 6.7 engine failure on another forum prompted the question. He used 10w30 non-synthetic oil which he stated was changed every 5000 miles. Traditional wisdom says this would be a good choice. My manual (2013) clearly states using 5w40 synthetic for severe duty service, which is described as extensive idling, lots if low speed driving, and towing heavy loads. This describes my driving as we travel extensively towing in the Western states. This is my second 6.7 and I've always used the 5w40, but also find it very strange that dealers (I always use them for the change) don't know what the manual says. I'm always questioned about the choice and show them the manual. I've gotten in the habit of calling ahead as many times they have to get the oil for my change. The manual also lists other choices, but specifically the 5w40 synthetic for severe duty. Why doesn't everyone do that for towing heavy 5th wheel trailers?

Just curious, how was it determined that the failure you mentioned was an oil related failure?

I don't know that I meet the requirements in the manual for the severe duty but I run Shell Rotella T6 in mine.

99% of diesels state to run 15/40 why would one use 10-30?? Did it mention what brand??

fla-gypsy wrote:Just curious, how was it determined that the failure you mentioned was an oil related failure?. I don't know if it was oil related, just got me thinking about it. The post said he manually downshifted going uphill towing to pass a slow moving truck. He threw a rod. His truck is in warranty at 18,000 miles.

rhagfo wrote:99% of diesels state to run 15/40 why would one use 10-30?? Did it mention what brand??I remember shopping for oil for the CRD and the parts store told me they started stocking Mobil 1 5W40 Turbo Diesel because the new Fords use it. My CRD manual says to use 0W40 Synthetic, or if unavailable, use 5W40. I switched to Amsoil 5W40 Full Saps, because the Mobile 1 didn't have the SAPS. The new Ram 1500 Diesel specs a 5W30 Low Saps oil due to the DPF. Look carefully at the oil nowadays and get one friendly for your rig.

Ford 6.7 - what oil do you use? | Good Sam Community

16 Replies

lenr
Explorer III
Jun 05, 2014
The factory break-in oil is 10W-30 semi-synthetic. My dealer only stocked 10W-30 and I had to educate them about 5W-40. 10W-30 is not approved by Ford for bio-diesel and it is hard to get away from bio-diesel. My baby (2012 F-350 6.7 Diesel) gets only 5W-40 because it’s what comes in full synthetic. Ford says towing 1000 mi. (presumably on an oil change) or idling 10 minutes an hour is “severe.” I qualify on both counts so 5W-40 still is needed. 15W-40 was “it” 10 years ago—times change, usually improve. 15W-40 is only approved down to 20 degrees. I want lots of flow ability at the colder temps. to lubricate on start up—again 5W-40.
txdutt
Explorer
Jun 05, 2014
The 6.7 Ford specifies the 10w-30 Diesel oil as the "normal" oil. It specs out 5W-40 or 15W-40 for severe use. Myself I run 15W-40 Apr-Oct & then 10W-30 the other 6 mos here in CO. If I lived in a warmer climate, I'd use the 15W-40 year round...
kennethwooster
Explorer
Jun 05, 2014
Been running Mobile 1 Delvac for years. Ran it in a 4wheel Case tractor with 855 Cummings. Couldn't believe the hours we put on it. Still not using oil when traded off. Probably ran 500 hours before changing. I did oil samples to determine drain period. Today in the 6.7 I still run Mobile Delvac 1, which is heavier then Mobile 1 for Diesels. I run the 5W 40, as Ford says.
NinerBikes
Explorer
Jun 04, 2014
Due to level of compression ratio's on diesels, and the resultant load on the whole engine package, I would always, if given the choice, run a full synthetic 5w-40 CJ-4 rated diesel oil.

I am convinced that the product known as Mobil 1 TDT is a superior product to Rotella T6, both in 5w-40. I know too many people that run the Rotella 5w-40 in little VW VE motored 1.9 Liter TDI's that have oil consumption problems between 10k mile oil changes, while the Mobil 1-TDT never drops on their dipstick. Usually the Rotella 6 fanboys need to add 1/2 a qt to a full qt by about 6 or 7000 miles, with another 3 or 4,000 to go before the next oil change.

YMMV, these have been my personal observations, and I've serviced and done oil changes on 100's of A4 1999-2003 VW Jetta ALH TDI motors.
nremtp143
Explorer
Jun 04, 2014
As long as the oil is CJ-4 compliant, it is ok. Then go by the temps you will be using the oil in if really concerned. Lots of people change types between winter and summer.
ib516
Explorer II
Jun 04, 2014
Page 50 HERE

10w30 (Normal Usage)
Turbo_Diesel_Du
Explorer
Jun 04, 2014
Maybe the 5W-30 was for a gasser? I've used 5W-40 or 15W-40 in every diesel I've had. JMHO
BB_TX
Nomad
Jun 04, 2014
MTPockets1 wrote:
.............
The post said he manually downshifted going uphill towing to pass a slow moving truck. He threw a rod. His truck is in warranty at 18,000 miles.

Makes me wonder just how he drives his truck. My 6.7 will down shift itself if I just press the throttle harder and it finds the right gear and RPMs to gain speed up a grade. No reason for manually shifting it down and forcing higher RPMs. I think I remember reading about an RPM limiter, but why risk pushing that limit.
Lynnmor
Explorer
Jun 04, 2014
rhagfo wrote:
99% of diesels state to run 15/40 why would one use 10-30?? Did it mention what brand??

Because the owners manual and the oil cap both say 10w-30.

That said, my stupid dealer put in more than 2 quarts too much of 15w-40 oil in the dead of winter during my first "free" oil change. I even showed him the oil cap before and after the change! Had him drain some out and then when I got home I drained 15.25 quarts out of my 13 quart engine. Never again.

I now do it myself using Rotella T6. Ford says to use 5-40 or 15-40 if using bio-diesel. Since it is getting hard to avoid the bio, I think that it would be best to use full synthetic 5w-40 at all times.
BenK
Explorer
Jun 04, 2014
Engine oil does other duties beside lube stuff...

Journal bearings for the crank use engine oil (PSI, GPH and the biggie: viscosity)
to keep the crank from going metal to metal...if floats the crank centered
on the block journal bore

The lower viscosity will have the journal oil get squished out by the power stroke
to go metal to metal

Not instant failure, but over time with enough metal to metal contacts...it will fail

Ditto the crank journal to connecting rods. If not enough GPH, PSI and viscosity
It will go metal to metal with no instant failure, but over time it will sooner

Another ditto for most of the other mating surfaces that depend on engine oil
to float it from going metal to metal

The first number is the viscosity 'behavior' of the engine oil at room temp

The second number is the viscosity 'behavior' of the engine oil at max spec temp

Viscosity is the thickness, but is more than just that. One key attribute
within that is film strength