Why is Rotella only available in strange weights?

[Gene K]

Originally Posted By: Ken2
Diesel engine oil is commonly sold in gallons, not quarts...gallon jugs or five gallon pails or 55 gallon drums. The prices cancov quoted are about right for a Full Synthetic oil. The conventional 15w40 oil is priced with other dinos.


Exactly. The "small standard container" is a gallon jug. The add mark on a CAT, Cummins or Detroit is 1-1.5 gallons down. Most truck diesels hold 10-12 gallons. The quart bottles only became available with the introduction of small diesels to the consumer market.

 

[Gene K]

Some of the large fleets that were running extended drains experienced a loss in the mileage they could go with the standard HDEO with the introduction of the 45% EGR Rate Engines. In order to get back to the same 4000 gallons of fuel use (Its common to use fuel use rather than mileage in extended drain programs) to change they went to T5 10W40. A side benefit has been a slight gain in fuel mileage. It can take 2 hours are longer for oil temps to peak.

In my experience the T5 10W40 has primarily been marketed in bulk.

 

[Gokhan]

Originally Posted By: Gene K
Originally Posted By: grampi
Typical motor oil weights are 5w30, 10w30, 10W-40, 20W-50, etc. Rotella comes in 5W-40, 15w40, and other oddball weights. I wonder why they don't make their oils in the typical weights?


Oil is built for an application. Diesel Trucks usually call for 15W40 or 5W40 Synthetic.

Here is how we got here:
Diesel oils had to be more shear stable with the pressures of cam driven injectors and gear driven cams and water pumps. When the first multis came out for these engines it wasnt possible to make a 10W40 that was stable enough so we ended up with 15W40.

15W40 became short-hand for Diesel Oil in the USA. Many Diesel Engine owners manuals specifically prohibit the use of 10W40 although they may allow the use of 10W30 in winter temps. When Synthetic came along and it was possible to build wider spread oils that were shear stable 5W40 allowed for the "Sidestepping" of the blanket prohibition on 10W40 in owners manuals.

PS Rotella T5 is available in 10W30.

Best answer to the original question.

You can make a shear-stable and low-volatility 15w40 from even the Group I basestocks. But not so for 10W-40 or xW-30.

Also, diesel engines require a larger minimum HTHS viscosity (> 3.5) to protect the bearings from high torques at low RPMs, which the gas engines aren't capable of. This mostly rules out 5w30 and thinner oils in large diesel engines.

So, the combination of high HTHS viscosity and shear stability (so that the HTHS viscosity can still stay high after a few hundred miles of driving) dictates 15w40 conventional or 5W-40 synthetic for diesel engines.

Pages 8 - 12 of this excellent presentation provide detailed answer to the original question:

Global perspective on base-oil quality by John Rosenbaum of Chevron (2010)

 

[blueiedgod]

I use Rotella 10W-40 in a bike. It is a great bike oil as well. It does not have friction modifiers commonly found in car oils, which will mess up the wet clutch friction plates. And since the engine and transmission share the oil, shear resistance is important for a bike oil.

 

[Gokhan]

Originally Posted By: blueiedgod
I use Rotella 10W-40 in a bike. It is a great bike oil as well. It does not have friction modifiers commonly found in car oils, which will mess up the wet clutch friction plates. And since the engine and transmission share the oil, shear resistance is important for a bike oil.

Rotella doesn't have friction modifiers or oils for wet clutches can't have friction modifiers is an Internet myth/old-wives' tale -- whatever you call it.

Almost every oil has friction modifiers, which is important for wear protection. Without friction modifiers, wear would increase, even in motorcycles. Rotella has about 50 ppm Mo according to various VOAs and used oil analysis.

Most oils, especially xW-40 and heavier weights, easily satisfy JASO MA. xW-40 and heavier oils have more friction to begin with because of their higher HTHS viscosity. Those that may have too little friction for wet clutches are some energy-conserving or resource-conserving (GF-4 or GF-5) xW-30/xW-20 oils. But you can't use these xW-30 and xW-20 weights in motorcycles anyway. Few oils have high levels of friction modifiers (such as 200 ppm Mo) and they wouldn't be appropriate for wet clutches.

In summary, most xW-40 and thicker oils would be OK with wet clutches.

Also note that too much friction would also be bad for wet clutches, as it would grab too hard. JASO MA puts both a minimum and a maximum on friction.

Here are the latest JASO MA, MA1, MA2, and MB specifications:

JASO MA/MA1/MA2/MB specification

 

[Steve S]

Originally Posted By: uart
Originally Posted By: bruno
Comes from living upside down !


Ok Australia, yeah I get it.

Just a little northern hemisphere humor!!!

 

[Steve S]

Originally Posted By: uart
Originally Posted By: bruno
Comes from living upside down !


Ok Australia, yeah I get it.

You should hear the Canadians talk about the southern hemisphere.