10-30 or 5-40 for MPG's?

[Toy4x4runner]

Which oil do should yield better mileage in my 6.0 ford diesel? Looking at either Delvac or Motorcraft 10-30 dino (CJ4/SM)or 5w-40 Mobil 1/Delvac/Rotella syn (CFJ4/SM). I drive a good mix of city and hwy, I'd say 60city/40hwy. Central FL climate. Don't normally tow/haul anything other than light junk like sofas and tree debre.

 

[Drew99GT]

I'd say 10w30. In your temperatures, it'll be thinner at all temperatures.

BUT, you might sacrifice a bit of wear protection.

 

[Pablo]

tree debre??

Didn't I date her once?

I say 10w30 IF that's OK by your OM.

 

[dnewton3]

I think you'll find 10w30 might offer some better fuel economy. I also believe that in "normal" use, the fear of higher wear is overstated.

Arkapigdiesel and I are both running Rotella 10w30 in our Dmax trucks. He racks up some reasonable mileage, and has posted UOAs. I don't hardly rack up enough miles, and my truck is relatively new, so I haven't done a UOA yet. I will do one as the mileage progresses, and will post in due time.

My next door neighbor also runs Rotella 10w30 in his '05 Ford 6.0L PS. I have posted a UOA for him here, some time ago. All came back well. The fear of a lighter grade oil shearing in the PS HEUI engine was unfounded, as the viscosity stayed right where it was.

The lighter grade oils in the HDEO world are sleepers; few know of, or credit them, their potential.

 

[D-Roc]

Originally Posted By: dnewton3
I think you'll find 10w30 might offer some better fuel economy. I also believe that in "normal" use, the fear of higher wear is overstated.

Arkapigdiesel and I are both running Rotella 10w30 in our Dmax trucks. He racks up some reasonable mileage, and has posted UOAs. I don't hardly rack up enough miles, and my truck is relatively new, so I haven't done a UOA yet. I will do one as the mileage progresses, and will post in due time.

My next door neighbor also runs Rotella 10w30 in his '05 Ford 6.0L PS. I have posted a UOA for him here, some time ago. All came back well. The fear of a lighter grade oil shearing in the PS HEUI engine was unfounded, as the viscosity stayed right where it was.

The lighter grade oils in the HDEO world are sleepers; few know of, or credit them, their potential.


Agreed...I am going to try a run of 10W30 here soon myself in my Dodge Cummins. Just not sure which brand yet, as 10W30 is a little harder to find than 15W40 HDEO. Probably Delo 10W30LE. If I do try a run, it will be CJ4 for sure.

 

[Jim Allen]

I concur with Pablo and dnewton3. Assuming "Funny Farm" isn't in a mostly hot climate, in which case a grade 40 would be an option, or necessary if the oil temps are consistently high. I'm using 10W30 in an older Ford diesel truck and in a 38 hp utility tractor with good results. The Ford truck seldom exceeds 200 degrees oil temp. Not sure about the tractor, but it isn't used all that hard so I doubt it's getting hotter than 200.

I'm beginning to see operating oil temps as a very important criteria in selecting lubricant viscosity. If you know the operating oil temp parameters of the engine and the specs on the oil, you can select a "three-bears-just-right" viscosity for the vehicle based on the climate and operating parameters. Not too thick, not too thin.

Check my reasoning here: Say your truck operates around 210 degrees oil temp. Your Rotella 10w30 has a viscosity of approximately 12.1 cSt at that temp. All is cool. But if your oil temp is more like 250, the 30 grade might have thinned to 9 cSt (or whatever, I don't have actual numbers here)into what amounts to a thick 20 grade. That's maybe a bit too thin for a diesel under load (or is it Dr. Hass?). At that 250 degree temp, a Rotella 40 grade, normally around 15cS @ 210, has thinned to about the same viscosity as the 30 was at 210. Again, cool. It seems as though the engine manufacturers must incorporate this dyno-derived info into their viscosity recommendations based on climate, which is all they can do because few vehicles have oil temp gauges.

Beyond this, shearing or thickening become factors over the OCI. UOAs or diligent research of UOAs in similar situations, can show if this will be a factor in your engine/oil combo.

Toy4x4runner: This last part wasn't EXACTLY a thread hijack, was it?

 

[Toy4x4runner]

thanks for the input guys. My 6.0 owners manual calls for 15-40 for trailer towing, but 10-30 is ok up to 90*F ambient temps. I'm located in Central FL, I-4 corridor. I do 4-5k OCI and keep a eye on things. Bigges thing for me... can't find 10-30 CJ-4 locally!! I could honestly get away with 75-90 M1 in the rear diff and 10-30 Delvac CJ4/dino in the engine and see some improvements for my typical use....

I really wish I could find a good Synthetic 5w30 CJ4/SM Oil. that would be Ideal. But all the big names either do 15w40 or 10/30 dinos and then 5w40 syns.

 

[dnewton3]

Your 6.0L PSD doesn't call for CJ-4, right? Just CI-4 or CI-4+?

There are several choices in a "synthetic" lighter grade diesel oil, including some excellent ones from Amsoil. Castrol has a 5w30 PAO synthetic HDEO in their Elixion product; bit hard to find and very pricey, though. If you ask me, unless you're doing extended oil drains, they're are a bit of overkill for your probable application.

If you have an AAP near you, they can order either the Rotella, Delvac 1300, or Delo in 10w30 dino oil. You may not get a "on sale" price, but it's not outrageous, either.

 

[Jim Allen]

Toy4x4runner: Do they have Menards stores in FL? They carry both 15W40 and 10W30 Rotella consistently and lately, they have been cheaper than my local Wal Mart, which always has 15W40 but sometimes 10W30 (not lately, tho). You might also try the Motorcraft 10W30 HDEO (CJ4), which I see at my Wal Mart.

 

[Toy4x4runner]

at my walmarts I only see 15-40 MC. that's what I"ve been buying lately.

 

[dnewton3]

Farm supply stores are another good source of good HDEO selections.

 

[bullwinkle]

I'd personally be a little concerned w/10W30 dino in summer in Florida, gets a little hot there! I'd go with the 5W40 syn, easier cold starts (not that it ever gets really cold there), with the higher 40 weight for summer, watch the shearing in the 6.0, I wouldn't go past 7500 miles w/out UOAs!

 

[Toy4x4runner]

I do 5k OCI. Might do the new M1 TDT that's CJ4/SM and Powerstroke approved. Just hit the shelves.

 

[ikeepmychevytoo]

Cross between -that the original question calling- is rather a complex one.

With 60% city milage and if your trips are rather short you might benefit more overall mpg with the 5W-40 despite the clearly worse hwy only milage. Especially with bigger engines where hot to cold milages tend to vary more.

I do many city milages. Even trips no less than 40mi I get similar milage with 0w30 Castrol SLX (no API energy conserving) with very economical thinner 5w30. In my case 0W takes up the slack.

 

[dnewton3]

The heat in Florida gets overplayed often. The average high in Orlando is 92 deg F in the summer. That's only 7 deg warmer, on average, then where I live in Indianapolis. Now, the desert SW might be a different story, but central FL is not THAT hot. It's humid, but it's not desert hot.

If he were towing heavy loads all the time in central FL, then perhaps a 15w40 would be a bit better. But that's not how the OP stated his use occured. He's very light if any towing, and 60% highway speeds.

A 10w30 will be fine, and would (slightly) elevate his fuel economy, which was the thrust of his original post (remember? a 10w30 vs. a 5w-40 what his question). After all, once up to temp, the grade achieved is a 40 vs 30. The lighter grade provides lower viscosity, which is the resistance to flow, or pumping. Less resistance = less energy required to overcome the resistance = less fuel consumed.

Plus, (and I don't know where this would "break even" at) the financial fuel savings from a 5w-40 "synthetic" would be somewhat negated by the more expensive lubricant, no? With a 10w30 HDEO, there is fuel savings AND lubricant savings.

 

[Toy4x4runner]

very well said dnewton3. That's exactly what I've been thinking... and very rarely does the heat get over 95* in the summer.

 

[rg200amp]

Originally Posted By: Toy4x4runner
Which oil do should yield better mileage in my 6.0 ford diesel? Looking at either Delvac or Motorcraft 10-30 dino (CJ4/SM)or 5w-40 Mobil 1/Delvac/Rotella syn (CFJ4/SM). I drive a good mix of city and hwy, I'd say 60city/40hwy. Central FL climate. Don't normally tow/haul anything other than light junk like sofas and tree debre.


Due to Ford trying to get better MPG out of there overall fleet, I would suspect the OEM oil weight will give you the best MPG and protection.

 

[Toy4x4runner]

I already am using 15w40 CJ4/SM Motorcraft w/Motorcraft filter. And you are right... I seem to get better MPG's vs say Rotella. But 10-30 Delvac or 10-30 Motorcraft should do me fine. Heck my owner's manual say 10-30 is acceptable to 90*F. They Recomend 15-40 for trailer towing though.

 

[rg200amp]

Use whatever brand you like. The OEM oil weight is what I think counts on MPG.

I hear Rotella is a good oil.

 

[D-Roc]

I think with that new Rotella you are going to have good results whichever viscosity you use, 10W30 or 15W40. Probably better mileage like everyone has said with 10W30 though. Past couple of uoa's that have floated in on this forum with Rotella 10W30 hasn't seemed to matter with regards to wear results whether it was 15W40 or 10W30.