15w40?
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 7,298
Likes: 45
From: Southern California
peppy, 15w40 has good flow characteristic's, especially compared to a straight weight oil. It could be you just noticed a sound that's been there for awhile. The only way to find out for sure is when you change it. But now that your ear is tuned to hear that rattle, it may persist even with a lighter weight of oil.
The 15w40 should be fine. But if it's gonna bug you worrying about it on your trip, then I would change to 10w30. 10w30 is more than adequate for most of our uses.
The 15w40 should be fine. But if it's gonna bug you worrying about it on your trip, then I would change to 10w30. 10w30 is more than adequate for most of our uses.
Postmaster
Joined: Dec 2003
Posts: 2,659
Likes: 2
From: S/C Texas
Thanks, I'll see how it goes till I leave. It just worries me that I'm stressing something. I dont wanna break anything 60 miles away from solid ground. Nothin but sand.
Like you said, it flows better than straight weights. Thanks, I'll worry a little less.
Like you said, it flows better than straight weights. Thanks, I'll worry a little less.
Postmaster
Joined: Aug 2001
Posts: 4,532
Likes: 5
From: Trussville, Alabama
FTE is a GREAT place to share ideas and opinions. But, don't forget about the oil companies web sites. there is a plethora of information available and lots to learn.....
Here is the page on Rotella T 15W40 http://www.rotella.com/products/rotella_t.html
I use it in my motorcycles. The absence of friction modifiers makes it nice for wet clutch applications.
Here is the page on Rotella T 15W40 http://www.rotella.com/products/rotella_t.html
I use it in my motorcycles. The absence of friction modifiers makes it nice for wet clutch applications.
Cargo Master
Joined: Jan 2004
Posts: 2,425
Likes: 697
From: Minnesota
acadianbob
i don't understand why you would want to use 15W-40. i don't think it provides any additional engine protection. i'm betting you'll see reduced fuel mileage do to pumping losses. i'd stick with the 5W-20.
Posting Guru
Joined: Jun 2003
Posts: 1,854
Likes: 1
From: Des Moines, Iowa
no way would i use 5w20 in my truck. i am thinking about the 5w40 though, and that would be as good on milage. but as you can see from my truck, mileage isn't all that much of a concern.
New User
Joined: Feb 2004
Posts: 18
Likes: 0
From: N.Cal
the SJ spec was a reduction in phospherous. The SL spec included added molybdenum disulphide, which is a real problem for wet clutches.
15w-40 oils are made for diesels, and are based on group-II and enhanced group-II base oils. They're excellent oils, so long as you're not starting your engine in temperatures below about 40 degrees. These oils are a clear step up in quality from mass-marketed 10w-30 and 10w-40 motor oils. If you live in Nebraska or Canada or some such place, I'd advise a 5w-40 for the winter.
15w-40 oils are made for diesels, and are based on group-II and enhanced group-II base oils. They're excellent oils, so long as you're not starting your engine in temperatures below about 40 degrees. These oils are a clear step up in quality from mass-marketed 10w-30 and 10w-40 motor oils. If you live in Nebraska or Canada or some such place, I'd advise a 5w-40 for the winter.
Postmaster
Joined: Dec 2003
Posts: 2,659
Likes: 2
From: S/C Texas
In 150 miles of road travel, truck drank up a quart of oil. In 80 miles of light to heavy off road, another quart of 15w40. I gave it a try.
Funny thing, went to my 70 year old mechanic (retired from GM after 30 some years of service) to renew my inspection sticker. I told him about my trying 15w40, instead of my regular 30w. He says "Follow me", opens the hood to his buick...."288,000 miles, 30weight oil", he says. Slams the hood, hand on my shoulder, "Go back to the 30w you were using before, quit messing with a good thing."
Funny thing, went to my 70 year old mechanic (retired from GM after 30 some years of service) to renew my inspection sticker. I told him about my trying 15w40, instead of my regular 30w. He says "Follow me", opens the hood to his buick...."288,000 miles, 30weight oil", he says. Slams the hood, hand on my shoulder, "Go back to the 30w you were using before, quit messing with a good thing."
Last edited by peppy; Feb 28, 2004 at 10:25 AM.
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Posting Guru
Joined: Jun 2003
Posts: 1,854
Likes: 1
From: Des Moines, Iowa
30w is not a good thing in temps below 60-50 degrees though. thats why multi vis. oils were made. your truck shouldn't use any oil that fast.
in the summer i will give either the 15w40 rotella T or the syn 5w40 rotella T oil. right now temps are still i the 30's
in the summer i will give either the 15w40 rotella T or the syn 5w40 rotella T oil. right now temps are still i the 30's
Postmaster
Joined: Dec 2003
Posts: 2,659
Likes: 2
From: S/C Texas
I'm thinking it used up the oil at its 15w or at least before opening up all the way to a 40 weight. Engine runs pretty cool.
The temps here get around mid 40's at night, and I'm almost always parked inside.
You're right, it shouldnt use oil that fast. It uses no oil at all with a 30 weight. Just with the 15w40.
I wish it didnt burn up the diesel oil, I'd love to make use of its benefits. But it does.
Maybe the diesel straight 30w is the way to go.
The temps here get around mid 40's at night, and I'm almost always parked inside.
You're right, it shouldnt use oil that fast. It uses no oil at all with a 30 weight. Just with the 15w40.
I wish it didnt burn up the diesel oil, I'd love to make use of its benefits. But it does.
Maybe the diesel straight 30w is the way to go.
Post Fiend
Joined: Jun 2001
Posts: 5,228
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From: Running Springs CA
Straight 30 is good down to 40F, according to the Castrol bottle and 32F according to 1990's GM owners manuals. Straight 30 solved the excessive oil usage on a 4.3 GM V-6. Single grade Rotella T and Delo 400 are commonly available here, but maybe not in all markets.
Jim
Jim
Freshman User
Joined: Mar 2004
Posts: 27
Likes: 0
Originally posted by Texan1983
no way would i use 5w20 in my truck. i am thinking about the 5w40 though, and that would be as good on milage. but as you can see from my truck, mileage isn't all that much of a concern.
no way would i use 5w20 in my truck. i am thinking about the 5w40 though, and that would be as good on milage. but as you can see from my truck, mileage isn't all that much of a concern.
Postmaster
Joined: Dec 2003
Posts: 2,659
Likes: 2
From: S/C Texas
Seems after 250 miles or so of the 15w40 Delvac, my possible valve train rattle is gone, and it stopped using it up. I guess it sheared down to its comfort level. 
If everyone keeps getting along inside there, I guess I'll be sticking with it.
I was looking at the Mobil/Delvac site again......anyone know why the multi-grade 1300 Super line is SJ/SL, but the monograde 1600 series is not?
http://www.mobil.com/USA-English/Lub..._1640_1650.asp
http://www.mobil.com/USA-English/Lub...c1300Super.asp
If everyone keeps getting along inside there, I guess I'll be sticking with it.
I was looking at the Mobil/Delvac site again......anyone know why the multi-grade 1300 Super line is SJ/SL, but the monograde 1600 series is not?
http://www.mobil.com/USA-English/Lub..._1640_1650.asp
http://www.mobil.com/USA-English/Lub...c1300Super.asp
Last edited by peppy; Mar 2, 2004 at 09:25 PM.