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15-40 VS 5-30

R

rick165

Member
heres one for you oil and engine experts i recently went back to a gasser in my work truck.the other was a duramaxx my new 2010 has the 6.0 liter.i have about a few gallons of 15-40 left over the 6.0 calls for 5-30.could i get by running the 15-40 in the summer months sence it wouldnt be so thick as it would on a cold winter morning just a thought.
RICK
 
I cant say on your truck but I thought that some 10w 40 would be ok in an older Pontiac with a quad 4. Wrong move, a head gasket later I decided that there was a reason the spec called for something special.
 
I work for a large utility company and we run 15W40 in everything, gas or diesel, large or small, winter or summer (in a northern state) without problems. My personal thought would be like yours, use it up in the summer.
 
just remember,, when your truck goes in for warranty work,they have a tendency to test the engine oil. is that 15w40 worth $10,000
 
I don't know nothin, but i would not 15-40 is still 15-40 in the summer. They want thinner oil for a reason. Maybe after you get 100,000 miles on it, but not now.
I am an old timer that grew up thinking that heavy oil was good, but that is not the way it works with modern engines.
 
The main reason why car and light truck makers use the thinnest oil possible - it go get the highest EPA fuel mileage figures. It has nothing to do with durability or longevity. The thinner the oil, the easier the cranshaft spins.

If anything, the 15W-40 is better for your engine unless you have to start it often at 20 below zero F. At those temps, you'll probably have fuel problems anyway.
 
The more I think about it I wonder if that heavy oil would reduce you mileage and waist enough fuel to pay of the oil you saved.
 
i dont think oil viscosity has anything to do with a head gasket. that was just a coincidence.
 
Besides the oil being thicker than recommended, the 15-40 diesel oil may still have fairly high level of ZDDP extreme pressure additive.

This additive is good for the engine internals, but bad for gas engine emission systems.

If you have emissions warrenty problems and they find that the oil fouled a sensor, cat converter or whatever, they might deny coverage because of the wrong oil.

Check the API oil spec in your operators manual and the one on the oil jug to see if they allow that spec oil in a 6L engine.
 
well i use 15-40 in my 6.0 liter in summer most time. this winter i dropped it off at the dealer to a service. i said put 10-30 in it.and he replied it requires 5-30 or it will affect warranty. i said the last time it saw 5-30 was when it was new. i said GM just wants the engines to wear out faster with that watery oil.i said put 10-30 in it.i just have a hard time believing them that 5-30 is required year round. i want a good film of oil between the brgs, as that is what is supporting the crank and cam,.. just a few thou. of oil .
 
I run 5W-30 Synthetic in my 2006 Dodge Cummins in the winter; my truck sits outside and cranks much better with the lighter oil. I am Northern New York, and temps can often get to -25 F. Sometimes -40.
The longer oil change interval (thanks to Low-sulphur fuel) helps make it a little less painful since I can go all of the coldest months with the Synthetic in one oil change.
 
When Ford first brought out their 4.6 OHC motor they were tested in taxi cabs. They were specified for 5W-30. The cab company still having older cars around that used 10W-40 used what they had on hand. The 4.6 OHC motor burnt the cam bearings in the head which are part of the head. This story was related to me by a good friend who ran an auto repair shop at the time. My 2 cent. It is your engine. You can do with it as you please BUT if a new vehicle and a warranty is involved you might be left holding a empty bucket with a hole in the bottom of it if you use the 15W-40. Some newer Fords require a 5W-20 oil. I also use this oil in my OLD B&S engine that in their day specified 10 weight oil in the winter and 20 in the summer.

Kent
 
more and more they are going to lighter oils to get the corporate fuel milege up (cafe).. If the engine will last over 100,000 miles then they dont care if it last longer. Actually they want to sell you another vehicle sooner as thats what they do. since 3/4 of the U.S. has cold starting winters, it also helps out there as well. Why in the world would gm or ford, want your truck to run for 300,000 miles??

Lighter oils can get you 2% better fuel economy and that across the entire fleet bumps up the average for the goverment requirements. Otherwise they have to go back and engineer smaller cars and more expensive technology on the engines to get it up there. Switching oil was a no brainer for the car companies.
 
I don't know that it would damage your engine and I don't know that it wouldn't. Why take a chance? Any potential repairs will be a lot more than the cost of using the recommended oil. If something goes wrong not caused by wrong the oil you'll always wonder. Sell the oil you have - Craig's list maybe - shouldn't be hard to do. All oils have different additives so it's also important to use the correct API rating.
 
Can you look in the owners manual? They usta have a chart for temps and weights. I dont have any new trucks so I cant look at one. They usta have a center line with black arrows pointing right or left according to the temp, then you choose the weight.
 
My 5.4 F250 says on the oil fill 5W20, Being old fashioned I just can't put that in, and pull a trailer at 2800 mile after mile. I do use 10W30, I want to use 15W40. In the County Seat Town North of me they use,(or did use) 15W40 in everything. A few years back they had a high speed chase, of almost 100 miles. State and local, 4.6 Fords and 350 Chevys the other car was a Mustang. Bottom line all All the State and Fed Cars with 5W20 got hot and dropped out. The Local Chevy that had 15W40 and the Mustang also had 15W40 Valvoline We found out later, he finally wrecked. Was all that was left at the end of the chase. I think it would be fine in the Spring.
 
Parts of that story sound highly questionable. Ford posted a durability study a few years ago and found that heavier oils helped engines last longer in every test. But, since the new engines are built well enough to last long past the warranty periods with lighter oils, they must be used to meed CAFE standards.
 
they told us in school that 5 wieght oil is not recomended in the diesels as it will knock the brgs out.
 
If you run 15w40 in a Ford 2.9 V-6, it will mess up the hydraulic lifters. Some engines are really picky on what weight oil you put in them, not sure why.
 
I read the Ford specs recently for their new 6.7 liter diesel that is actually built by Ford instead of IH-Navistar.

One of the oils that Ford lists for it - is 15W-40. Here's the list.

Motorcraft® SAE 0W-30 Super All Season Motor Oil
XO-0W30-LAS or equivalent

Motorcraft® SAE 5W-40 Full Synthetic Diesel Motor Oil

Motorcraft® SAE 10W-30 Super Duty Diesel Motor Oil

Motorcraft® SAE 15W-40 Super Duty Diesel Motor Oil
 
Machining procedures have improved greatly and tolerances and clearances have been tightened quite a bit, such as bearing clearances. Run heavy oil in bearings with tight clearances and you run the risk of spinning bearings. It's not unusual these days to pull a modern gasser down with over 100K and it's in very good shape, if it's been run with the right oil and changed often. The days of big tolerance ranges and long break-in periods are long gone. Mileage and longevity standards, new regs for cat converters, use of roller cams, all factor in.
 
You run the risk of having cam phasing issues using 15-40. Nearly all new gas engines have the ability to adjust the camshaft timing for better performance/fuel economy and the elimination of the EGR valve. Using the wrong viscosity can cause the cam phasing to be slower than required. Use the correct weight of oil and save the 15-40 for your tractors.
The reason 15-40 is shown for use in the new Ford produced Powerstroke is if you're running it on B-20, otherwise they want you to run 10-30 diesel rated oil.
 
I have one barrel of John Deere 15-40 Plus 50 oil. I use it in every engine I own. I have done so for over fifteen years that the Plus 50 oil came out. 1990 Dodge W350 5.9 Cummins 350,000 mile, 1990 Olds 98 3800 226,000 miles, 2001 Grand AM 3400 196,000 miles, 2006 Chev K3500 Duromax 265,000 miles. Wife"s 2008 Dodge Challenger has had the 15-40 every since the first oil change.

I live in Northern Iowa. I think the biggest thing is if you warm your engine up before driving. If you jump in and take off like a drag race then you would want a thinner oil. My wife and I both let our vehicles warm up a few minutes before driving them in cold weather. It must work as I have never had a bottom end engine failure in my sixty years. Most of my cars and trucks have had over two hundred thousand miles on them before we quit driving them.
 
If you use it, and have engine failure, the cost will be on you, not the dealer. They will test the oil, and give you the bill. Is using up the oil you have on hand worth the 10,000 dollar risk? Your call. Tom
 
I put some 15 40 in my Ford truck last year and got some erratic oil pressure readings for a while.Truck had 170,000.Im not convinsed that I should use it in winter.Better use the the 5 30. Been burning oil since the mid 50s.
 
If your under warranty stay with the 5w30 after the warranty stay with the 5w30 or could use the 15w40 in the summer but mileage will suffer some and with the 6.0 you need all the mileage you can get.

that engine does not "need" that thick of oil after the 15/40 is gone stay with the 5/30.
 
JD oil's are of very [u:e7268e189a]high quality[/u:e7268e189a] packaged partially by ExxonMobil.
 
A friend in Oakland MD got a new engine from Walmart due to the wrong oil. The day after his oil was changed the temps dropped to 5 below. He started his truck to got to work and made it aboit a half mile. The valves contacted the pistons and all heck broke loose. He returned the truck to the dealer due to the warranty. The dealer tested the oil and found 10-40 in the crankcase. Walmart paid for the new engine, but there were no winners here. He was out of a truck for a month and Walmart paid for an engine.

I can supply his name if you need but I am not sure if he would like it posted publicly.

Aaron
 
thanks for all your replys.i decided to stay with 5-30 for 26 bucks a change it aint worth taken a chance on thanks.
RICK
 
(quoted from post at 09:42:47 01/01/11) Besides the oil being thicker than recommended, the 15-40 diesel oil may still have fairly high level of ZDDP extreme pressure additive.

This additive is good for the engine internals, but bad for gas engine emission systems.

If you have emissions warrenty problems and they find that the oil fouled a sensor, cat converter or whatever, they might deny coverage because of the wrong oil.

Check the API oil spec in your operators manual and the one on the oil jug to see if they allow that spec oil in a 6L engine.
Click to expand...

the new diesel semis are still useing 15-40 and they have more emissions crap on them than your average car - average car has - egr system, cat, and thats about it modern diesel has much more that you have the dpf, the cat, the egr system, the system for urea injection, the system for mobile regen of the dpf etc - im not saying use or dont use your 15-40 i just wanted to put that out there
 
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