No Rotella T6

[Snobdds]

The different groups do compare mineral oil to synthetic:

Base Oil Groups Explained

Then it's a moot point and again, why do they even make 15w40 anymore?

 

[ruffdog]

Then it's a moot point and again, why do they even make 15w40 anymore?

Because it is the mineral oil viscosity that some manufactures call for in warmer weather.

 

[greenrider1]

I prefer T6 15w-40 in my 2003 Duramax simply because it stopped consuming oil. It never used very much to begin with, maybe half a quart every 5k miles, but the 15w-40 seems to have stopped this completely. This truck is not a daily driver but regularly tows a heavy 16,000 lb 5th wheel 3 seasons out of the year. It rarely gets driven in the winter and lives in a heated barn, so thinner oil is of no benefit to me. Strange thing is my oil pressure is slightly higher according to the gauge when at operating temp when compared to 5w-40 T6, even though theoretically they're both 40 weights.

 

[Snobdds]

Because it is the mineral oil viscosity that some manufactures call for in warmer weather.

15w40 and 5w40 are the same at operating temp. That is what the "40" signifies.

 

[pmsmechanic]

It was explained to me this way. Take a 0w-40 oil. 0 means that it lubricates the same as a straight 0 weight oil. w stands for winter and the 40 means that it lubricates the same as a straight 40 weight oil when it's hot outside. It's not the oil itself that has those properties. It's the additives added to the oil that let it lubricate as well as a straight weight oil. I was told that the designation (ie. 0w-40) has nothing to do with the actual viscosity of a multi grade oil.

 

[MossRoad]

All T4 & T5
Any T6?

Nope. Lotta bare shelves in that section.

 

[CADplans]

was told that the designation (ie. 0w-40) has nothing to do with the actual viscosity of a multi grade oil.

0W-40 has EVERYTHING to do with the viscosity,,
but, my fingers are too tired to type the explanation ,, again,,

 

[MossRoad]

Me?
The thread title is “no Rotella T6”

No. That wasn't directed at you.

 

[jyoutz]

Was at O’Reilley’s and tractor supply today. Two gallons of Delvac at the first place and some travelers at TSC. Pretty much bare shelves.

 

[jyoutz]

Because it is the mineral oil viscosity that some manufactures call for in warmer weather.

Based on what was available at the time of the equipment manufacture. 40 weight is 40 weight, so the lubricant properties of the oils are the same for warm weather. It’s just the winter performance that differs. I agree: why make 15w-40 oil anymore?