15w40 vs 10w30 vs 5w40

[rufushusky]

Originally Posted By: dnewton3
Is that for Delvac 1300?

$11 - $5 Mobil Rebate = $6/gallon. That's SICK!


Yep...noticed it right after I changed my oil...

http://specials.napaecatalog.com/WebProject.asp?CodeId=7.5.5.5#

 

[dnewton3]

Well - it's actually (nearly) $12/gallon, but still a great price with a @5 rebate!

 

[rufushusky]

Originally Posted By: dnewton3
Well - it's actually (nearly) $12/gallon, but still a great price with a @5 rebate!


I must have been factoring in my AAA discount!

But like you said great price.

 

[Gokhan]

Originally Posted By: Chris142
My new to me pickup only recomends 2 oils. 15w40 and SAE30. Gonna forget about SAE30 for now.

Would a 10w30 Diesel oil give it any better mpg? Power? It is kinda gutless w/o a turbo.

5w40? Those only come in Synthetic don't they?

Recomended OCI is 2500 miles. Personally I don't see why the currant fill of Delo 15w40 can't safely go 6-8k.

Make sure it's API CJ4. That ensures that the HTHS viscosity is at least 3.5 cP, which is the most critical spec for a diesel oil's protection on soot-induced wear.

If you use 5W-40, you might squeeze a little longer OCI, as it's fully synthetic. It will also give slightly more fuel economy than 15w40 and be better for winter starts. Shell Rotella T6 5W-40 sells pretty cheap at Wal-Mart and it's an excellent oil. But then 15w40 will also be perfectly fine with that engine. My favorite is Mobil Delvac Super 1300 15w40. It's arguably better than Chevron Delo (better base oil and additive package). You can easily go for 5000 miles on either oil.

Rotella T5 10w30 would be OK too. It's semisynthetic. It would slightly beat 15w40 in fuel economy and power also slightly improve over 5W-40 in that respect as well.

Again, Mobil Delvac 1300 Super 15w40 (HTHS = 4.3 cP) is perfectly fine. Shell Rotella T6 5W-40 (HTHS ~ 3.7 cP) may be an improvement but since it's slightly thinner, soot-induced wear may increase slightly. CJ-4 10w30 (HTHS ~ 3.5 cP) is slightly thinner than 5W-40 and soot-induced wear may increase even slightly more. Also, 15w40 will require less top-offs than 5W-40, which will in turn require much less top-offs than 10w30.

 

[Jim Allen]

I wanted to update this with some new (old) info. I found some followup lubricant information, both in a 1987 TSB and in the '86 PDI, Lubrication and Maintenance Manual for Ford Trucks, that Ford began recommending 15W40 over 10W30 in the 6.9L sometime in '86. The TSB mentions the 15W40 Motorcraft Super Duty oil (green can) by name and mentions "beneficial qualities not yet covered by API classifications," which might mean the API CF classification which was just around the corner then. API CD was the best diesel classification at that point. So, it looks like 15W40 came into "official" favor with Ford for the IDIs sometime in the '86-87 timeframe.

 

[bullwinkle]

Noticed that GM did the same thing, about the same time, my '85 6.2 manual recommended SAE 30 for constant use or 10W30 in winter, and the '93 6.2 manual recommended 15W40 for constant use or 10W30 in winter. The HDEOs of today are so far beyond what they had in the '80s, along with ULSD fuel-a huge improvement over the old days.

 

[Garak]

Originally Posted By: bullwinkle
Noticed that GM did the same thing, about the same time, my '85 6.2 manual recommended SAE 30 for constant use or 10W30 in winter, and the '93 6.2 manual recommended 15W40 for constant use or 10W30 in winter.


Back in the 1980s (he had around a 1985 6.2, too), my dad used 15w40 in the summer and 10w30 in winter. He absolutely loathed straight grades and wouldn't even use them in outdoor power equipment.

 

[bullwinkle]

Guess we're a (little) luckier down here-it doesn't get very cold here any more, I could have even skipped the snow tires this year. I just run the straight 30 because I have so much of it, and it seems to work just as well in the IDI diesels as anything else does-if they were run a lot more miles & hours in colder temps between OCIs it would be better to run 15W40.

 

[dnewton3]

Depending upon region, straight grades can make a lot of sense, or can be an afterthought.

One of our members (Ottomatic) had a 6.9L IDI Ford with 450,000 miles on it, when it got stolen. Was still running fine, never had so much as a valve cover off, running nothing but 4k mile OCIs with PZ LongLife 30 grade. He was in FL, where cold starts are never an issue.

 

[Garak]

Originally Posted By: bullwinkle
I just run the straight 30 because I have so much of it, and it seems to work just as well in the IDI diesels as anything else does-if they were run a lot more miles & hours in colder temps between OCIs it would be better to run 15W40.


I'm sure my dad could have easily gotten away with straight 30 through the summers. He just hated straight grades long before we, as a group, started looking down our noses upon them.

I think the only concession he ever allowed for straight grades was with air compressors that required ISO 68 or such things. Generators, no. Lawnmowers, no. Absolutely ancient tractors on the farm, no....

 

[ottomatic]

Originally Posted By: Chris142
Originally Posted By: tpitcher
More vehicle & engine detail please...

87 F250,6.9l diesel no turbo, 4 speed with 3.55 gears. I plan on using it to take trash to the dump and dirt bikes out to the desert.


I used Pennzoil HD 30 & Fram filters in my 86 6.9 from the time I bought it brand new till it was stolen in 98 with 450,000 mi on it. I would recomend the 30wt.

BTW Truck did spend most of it's life in Ny. Sometimes 10 below and never had a starting issue



https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=866053&page=1

 

[GBL]

I stumbled across this recently regarding the mandated federal change to 10w30 by 2017. Perhaps it has been mentioned herein previously but I couldn't find it.

http://www.arkansastrucking.com/assets/m...resentation.pdf

Their limited testing indicated no change in engine longevity by doing so.

This mandated change is expected to increase the fuel economy by at least 2%. Assuming $4/gal diesel, OCI of 10k and 14mpg this would save $57 at each oil change. Consequently, the fuel savings would pay for the oil change using such parameters.

This seems to justify those who are using the 10w30 already.

 

[Jim Allen]

Thanks for posting that. No doubt we'll see the same Chicken-Littling, foot-dragging, old-school thinking that we still see regarding 5W20 oils but eventually it will fade away. Personally, I'm waiting for the advent of the 5W30 HDEOs. They are available now but are pricey. I'd like to see a 5W30 HDEO on the shelves as commonly as I can find 10W30.

 

[A_Harman]

Originally Posted By: GBL
I stumbled across this recently regarding the mandated federal change to 10w30 by 2017. Perhaps it has been mentioned herein previously but I couldn't find it.

http://www.arkansastrucking.com/assets/m...resentation.pdf

Their limited testing indicated no change in engine longevity by doing so.

This mandated change is expected to increase the fuel economy by at least 2%. Assuming $4/gal diesel, OCI of 10k and 14mpg this would save $57 at each oil change. Consequently, the fuel savings would pay for the oil change using such parameters.

This seems to justify those who are using the 10w30 already.



I went through the presentation, but did not see any mention that the Feds have mandated a change to 10w30 HDEO. Are you just referring to fuel economy standards for heavy trucks?

 

[A_Harman]

Originally Posted By: Jim Allen
Thanks for posting that. No doubt we'll see the same Chicken-Littling, foot-dragging, old-school thinking that we still see regarding 5W20 oils but eventually it will fade away. Personally, I'm waiting for the advent of the 5W30 HDEOs. They are available now but are pricey. I'd like to see a 5W30 HDEO on the shelves as commonly as I can find 10W30.


I would consider using a full-synthetic 5w30 diesel oil in my truck, as long as its HTHS was 3.7 or higher. Even if new engines are designed for used with 10w30, 15w40 will still be needed for old engines, so it won't go away quickly, if ever.

 

[GBL]

See slide 4 for the 10w30 requirement.

 

[GBL]

Originally Posted By: A_Harman
Originally Posted By: Jim Allen
Thanks for posting that. No doubt we'll see the same Chicken-Littling, foot-dragging, old-school thinking that we still see regarding 5W20 oils but eventually it will fade away. Personally, I'm waiting for the advent of the 5W30 HDEOs. They are available now but are pricey. I'd like to see a 5W30 HDEO on the shelves as commonly as I can find 10W30.


I would consider using a full-synthetic 5w30 diesel oil in my truck, as long as its HTHS was 3.7 or higher. Even if new engines are designed for used with 10w30, 15w40 will still be needed for old engines, so it won't go away quickly, if ever.


Some of the current engine manufacturers allow 10w30 based on the temperature. How would they change the engineering on such to allow the 10w30 vs. the 15w40?

 

[A_Harman]

Typically heavy duty diesels are designed to work with oils that have HTHS of at least 3.7. This is easy for a 15w40 grade, but not so easy for a 10w30. 5w30's with that high of an HTHS are rare. If diesel manufacturers need to start designing engines to conform to a mandated oil with lower HTHS, the bearing sizes may need to be increased, and all design calculations related to cam follower oil film thickness would need to be reviewed, possibly leading to redesign of the cam lobes.

 

[A_Harman]

Originally Posted By: GBL
See slide 4 for the 10w30 requirement.


That's an API requirement, not EPA. Maybe a fine distinction, as the EPA truck fuel economy standards are pushing it, but the Feds aren't telling us what to put in our crankcases (yet).