Rotella "T" Causing Injector Problems??
Post Fiend
Joined: Jun 2004
Posts: 9,293
Likes: 10
From: Parker, CO
RMPC, do you know what the actual difference is between 15w-40 and 5w-40?
The numbers are the viscosity rating. The two numbers indicate that the oil is a multi-weight. Meaning that the first number is the viscosity at a cold temperature, and the second number is the viscosity at normal operating temperature.
At operating temperatures, both oils are EXACTLY IDENTICAL. The difference is the first number, which is the viscocity at cold temps. The 5w-40 will flow better at colder temps, which is why many folks no longer have cold start romps in the winter when using 5w-40 oils. Once both oils warm up, the viscosity is the same, meaning that neither oil will thin past the point of their rating.
So 5w-40 is only thinner and flows easier at colder temperatures than 15w-40. When both reach operating temperature, they both flow the same and neither one is thinner than the other.
The numbers are the viscosity rating. The two numbers indicate that the oil is a multi-weight. Meaning that the first number is the viscosity at a cold temperature, and the second number is the viscosity at normal operating temperature.
At operating temperatures, both oils are EXACTLY IDENTICAL. The difference is the first number, which is the viscocity at cold temps. The 5w-40 will flow better at colder temps, which is why many folks no longer have cold start romps in the winter when using 5w-40 oils. Once both oils warm up, the viscosity is the same, meaning that neither oil will thin past the point of their rating.
So 5w-40 is only thinner and flows easier at colder temperatures than 15w-40. When both reach operating temperature, they both flow the same and neither one is thinner than the other.
Post Fiend
Joined: Feb 2002
Posts: 10,600
Likes: 3
From: Carhenge
Originally Posted by RMPC
We are both curious to see how long one will last commercially with 5w 40 in the west with desert heat and mountains pulling 10,000 to 18,000 lb fith wheel campers every day, with the go pedal often pinned to the floor for long periods of time. It might be ok for a grocery getter or in cooler climates..... we'll see
Don't believe me? do a little research into viscosity index of oils. The higher an oil's viscosity index, the more slowly it thins with increasing temperature. Rotella T 15-40 has a viscosity index of 141, Rotella T 5w-40 has a viscosity index of 176 per Shell's web site.
Senior User
Joined: Oct 2006
Posts: 174
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From: Mountains of N. Montana
Ok you guys win 
I havent looked into the Shell web site and maybe they've come up with some magic in the last few years... I was hesatant to use a multi grade ie: 15 40 when it came out...too, I just am living on 20 plus years of wrenching on diesels that drank straight 30 wt stuff and have tractors in the family that have many thousands of engine hours on em from the 60's and are still going and never had the pan off. I suppose I should go along with the 21st century but still feel in my gut that the old school stuff will last longer. Not everyone can afford a 50,000.00 truck with a computer making all the decisions. When it quits making the proper decisions and I have to walk home... I'm getting back into my mechanical engined truck thats been around for years, and will be around long after the electron brained one has bit the dust...I can fix my no start problems with a piece of bailing wire or string.... can you?
I havent looked into the Shell web site and maybe they've come up with some magic in the last few years... I was hesatant to use a multi grade ie: 15 40 when it came out...too, I just am living on 20 plus years of wrenching on diesels that drank straight 30 wt stuff and have tractors in the family that have many thousands of engine hours on em from the 60's and are still going and never had the pan off. I suppose I should go along with the 21st century but still feel in my gut that the old school stuff will last longer. Not everyone can afford a 50,000.00 truck with a computer making all the decisions. When it quits making the proper decisions and I have to walk home... I'm getting back into my mechanical engined truck thats been around for years, and will be around long after the electron brained one has bit the dust...I can fix my no start problems with a piece of bailing wire or string.... can you?
Thread Starter
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Senior User
Joined: Feb 2006
Posts: 207
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From: Somerset County, PA
Sheeze!! Okay, 5w-40 "T" synthetic is in there. So far, so good. We haven't had any really cold mornings yet to see how it affects start-up, but, in my various John Deere diesel stuff, there's noticeably easier cold-weather starts vs the 15-40 (various brands) that was in them before the change.
Thanks for all the responses.
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
??????
I always heard that to make a multi-viscosity oil you started with the thinner oils and added polymers that expanded when hot to simulate the thicker oils behavior. A 5-40 weight oil is just that: A 5 weight oil that has additives in it. Nothing wrong with that, but the difference comes in when the oil reaches the end of it's service life. The polymers get sheared down and you no longer have 5-40 but more like 5-20 weight oil.
It's made me very disciplined about frequent oil changes and not really caring whether I have a bypass filter or not. I change the oil way more often than Ford recommends to keep everything fresh.
I always heard that to make a multi-viscosity oil you started with the thinner oils and added polymers that expanded when hot to simulate the thicker oils behavior. A 5-40 weight oil is just that: A 5 weight oil that has additives in it. Nothing wrong with that, but the difference comes in when the oil reaches the end of it's service life. The polymers get sheared down and you no longer have 5-40 but more like 5-20 weight oil.
It's made me very disciplined about frequent oil changes and not really caring whether I have a bypass filter or not. I change the oil way more often than Ford recommends to keep everything fresh.
Post Fiend
Joined: Jun 2004
Posts: 9,293
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From: Parker, CO
Dan, I think that was a bigger problem when multi grade oils first came out. The technology now keeps those polymers from breaking down as easily to maintain the oil viscosity for a longer interval. Eventually they do break down, no matter what the weight of the oil, and thin out over time. Synthetics tend to resist breakdown for longer periods of time, simply because of the nature of dino oil itself. Running an oil analysis like Blackstone will tell you how your oil is holding up and how long you can safely run you oil before it breaks down too much.
Post Fiend
Joined: Feb 2002
Posts: 10,600
Likes: 3
From: Carhenge
Originally Posted by Kwikkordead
??????
I always heard that to make a multi-viscosity oil you started with the thinner oils and added polymers that expanded when hot to simulate the thicker oils behavior. A 5-40 weight oil is just that: A 5 weight oil that has additives in it. Nothing wrong with that, but the difference comes in when the oil reaches the end of it's service life. The polymers get sheared down and you no longer have 5-40 but more like 5-20 weight oil.
I always heard that to make a multi-viscosity oil you started with the thinner oils and added polymers that expanded when hot to simulate the thicker oils behavior. A 5-40 weight oil is just that: A 5 weight oil that has additives in it. Nothing wrong with that, but the difference comes in when the oil reaches the end of it's service life. The polymers get sheared down and you no longer have 5-40 but more like 5-20 weight oil.
Originally Posted by dt444e
yes its five times the weight of water at start up and forty times the weight of water at 100 degrees F.
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Senior User
Joined: Mar 2006
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From: Northwest OH
Viscosity of Synthetic Rotella 5w40
40(Degrees C)=90
100(Degrees C)=15.0
Neutralization=11.5
Viscosity of regular (Dino) Rotella 15w40
40(Degrees C)=120
100(Degrees C)=15.5
Neutralization=10.1
Sounds like the Synthetic (Pronounced Sin-thet-ick=not extra refined dino as noted in a previous post) is superior in terms of reasonably lower startup viscosity and is nearly the same viscosity at operating temperatures, not to mention that it has a higher capacity to neutralize the resulting combustion acids - which would theoretically mean slightly longer oil change intervals with better protection. Synthetics are more resistent to prolonged high temperature running.
40(Degrees C)=90
100(Degrees C)=15.0
Neutralization=11.5
Viscosity of regular (Dino) Rotella 15w40
40(Degrees C)=120
100(Degrees C)=15.5
Neutralization=10.1
Sounds like the Synthetic (Pronounced Sin-thet-ick=not extra refined dino as noted in a previous post) is superior in terms of reasonably lower startup viscosity and is nearly the same viscosity at operating temperatures, not to mention that it has a higher capacity to neutralize the resulting combustion acids - which would theoretically mean slightly longer oil change intervals with better protection. Synthetics are more resistent to prolonged high temperature running.
Fleet Mechanic
Joined: Sep 2006
Posts: 1,329
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From: IN
Originally Posted by RMPC
May be... I just havent seen one with a lot of miles on it yet (over 250,000).
Junior User
Joined: Nov 2004
Posts: 98
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That's funny, I always thought oil was lighter than water, that's why it floats. Forty times the weight of water, that would be like 360 pounds per gallon. Heavy stuff. [/QUOTE]
come on "clux" viscosity not weight this discussion doesn't need to be as scientific as everyone is making it out to be.
[/QUOTE]come on "clux" viscosity not weight this discussion doesn't need to be as scientific as everyone is making it out to be.
Senior User
Joined: Sep 2006
Posts: 151
Likes: 0
hmmm....
That's over 873 miles a day. That's nearly 16 hours of nonstop running at 55 miles an hour, with no stops for traffic or refueling. I'm gonna have to whip out the ole' flag on that one. Photoshop or a tampered odometer.
I've tampered with an odometer when returning a rental car in Hawaii after a trip to Shanghai, and I used photoshop on my Oxford transcript when applying to grad school at South Austin Tehcnical Community College of Arts, so I know both can be done
That's over 873 miles a day. That's nearly 16 hours of nonstop running at 55 miles an hour, with no stops for traffic or refueling. I'm gonna have to whip out the ole' flag on that one. Photoshop or a tampered odometer.
I've tampered with an odometer when returning a rental car in Hawaii after a trip to Shanghai, and I used photoshop on my Oxford transcript when applying to grad school at South Austin Tehcnical Community College of Arts, so I know both can be done
Post Fiend
Joined: Feb 2002
Posts: 10,600
Likes: 3
From: Carhenge
Originally Posted by dt444e
come on "clux" viscosity not weight this discussion doesn't need to be as scientific as everyone is making it out to be.
