Ok, I'll muddy the waters a little more. I used some Schaeffer oil in the past, but didn't really stick to it. Can't recall why I didn't stick with it. That was quite a few years ago. I decided to check in to Schaeffer again. I can get their Series 9000 5w40 full synthetic $1080 a 55 drum, 3% off for buying in bulk drum, delivered free to my door and free oil sample kits thrown in. That equates to $19.04 a gallon for full synthetic, and free oil sample kits to sweeten the deal! Schaeffer is a very good oil, and the pricing can't be beat, so I am moving over to Schaeffer. Their Series 7000 15w40 synthetic blend is $130 a drum cheaper, with the same 3% off and free oil sample kits. So that is around $16.75 a gallon delivered to the door for free.

Schaeffer Oil | Synthetic Motor Oils, Engine Oils, Diesel Fuel Additives, Industrial Lubricants Manufacturer

The Series 9000 full synthetic.... Schaeffer Oil | Supreme 9000 Full Synthetic Heavy Duty Engine Oil

The Series 7000 Syn Blend...... Schaeffer Oil | Supreme 7000 15W-40 Synthetic Blend Motor Oil

Shaffer is a very good oil and it's hard to go wrong with it.

I just bought the full synthetic version of the house brand oil I've been using for something like $650 for a 55 gallon drum. The oil company says their customers that use it absolutely love it. I have one more change to do with the last of the non synthetic (plus I had to do my post in-frame break-in with non-syn oil) and then I'll be trying out the new stuff. I have to buy my oil sample kits, but they are only $8 and are processed by a Valvoline lab.

You will get many opinions as to which oil to run. I like mobile1. You can go to walmart and buy mobile1 full synthetic for like 30 bucks a jug. I have the 4.7 so not sure how many quarts the HEMI takes (7?) but a jug for 30 and a couple quarts and an oil filter and your good to go

On that scale, it wouldn't be a bad thing. At 10 gallons an oil change in my class 8, harder to swallow. I just got a 30 gallon drum of Schaeffer 7000 semi syn 15w40, a 12 quart case of 5w30 full synthetic for my 2013 pickup, a 5 gallon can of their winter fuel additive (one pint to 125 gallons of fuel), 4 oil sample kits, a 12 can case of their Citrol degreaser (which is a killer product and is biodegradable), all delivered to the front door of my home by Fed Ex, for a total of $907 including tax. Not bad package for the price.

I change oil every 10,000 miles. some times go to 11,000 never been to 12,000. just am ole habit.

Bingo on "full synthetic." Regardless whether its gasoline or diesel engine, you must know how to decipher the API (American Petroleum Institute) code specs on engine oil. The vast majority of enigine oil will have "S" or "C" as the first letter API spec. "S" means spark ignition. gasoline, propane, methane, CNG are engines with spark plugs. Diesel is the only engine that has no spark plug. It ignites the diesel by compression, which is what "C" API spec signifies. If the oil only says "S" and not "S" and "C," this oil WILL DAMAGE your diesel engine. Engines with spark plugs have around 7:1 to 10:1 -- meaning when the piston is at its lowest position, the space volume is compressed to 10% at TDC (top dead center) as the piston moves up. Before it reaches TDC, the spark plug ignites the fuel to begin the power stroke. In 7:1 compression ratio, its 14% of BDC (bottom dead center) which is when the piston is at its lowest position. A diesel engine has a higher compression ratio of 15:1 to 20:1 -- twice of gasoline engines !! As air molecules are compressed in milli-seconds, they rub and create friction heat. This friction heat between air molecules is sufficient to ignite the diesel fuel. The fuel injector sprays a fine mist of diesel just before the piston reaches TDC, so the heat combines with diesel to start the power stroke cycle.
This high compression stroke is what API "C" rating is chemically designed to handle, which "S" rating can't handle. When you put "S" oil in diesel engines, the compression rings and oil rings on the piston will suffer premature wear, resulting in blow-by. This is when your exhaust is showing more smoke from unburned diesel AND there's a bluish tint, which is oil mixed with the exhaust.[ATTACH=CONFIG]1308[/ATTACH]
The 2nd letter after "C" is the engine protection additives, such as friction reducer, anti-foam, anti-rust, anti-sludge reducer, etc... the higher the 2nd letter, the more advance are the engine protection quality. For example, "CF" will offer more advance protection than "CE" or "CB"
The numbers such as 20W-40 or 5W-30 corresponds to season. In sub-zero engine start ups, "W" means winter application, so 5W is ideal for -20ºF start up while 20W is for 30ºF snow condition. The 2nd number in 10W-50 is summer heat condition. The higher the 2nd number, the more it will handle hot desert operation. 10W-50 is better to handle hot desert heat than 30 weight oil (cheapest in the market). IMO, 30 weight should only be for engines that leak oil, and make sure its has the "C" rating for diesel engines. [ATTACH=CONFIG]1309[/ATTACH]
Finally, the reason "full synthetic" is best is because of why it was developed. Multi-grade oil like 10W-50 was first developed for aircraft in WW2, then it was later declassified as a military secret and made available to the general market. Full synthetic was developed for formula race cars and stock car race applications. We're talking over 100_mph speed for 3 hours non-stop. The auto industry like Ford, Chrysler, GM were strongly opposed to marketing full synthetic to the general public because it would prolong engine life and decrease car sales. Cars & trucks lasting longer means people would have no reason to junk their old cars & trucks when it can last over one million miles. You might want to use a magnifying glass to see the two picts I posted.

Disagree to some extent. The first number, is correct in that it is a measure of the winter flow rate (as that is what the "w" in the specification means... winter). The second number has nothing to do with summer. It is a measure of the viscosity rating of the oil at 100cSt temperature, or better known as the normal operating temperature of the engine. A 5w40, a 15w40, or a straight 40 are all 40 weight oils with different winter flow characteristics but have the same viscosity at engine operating temperature. In other words, they would all work just fine in a summertime Death Valley type of operation in an engine designed for a 40 weight oil.

The weight of the oil (the number after the "w") has nothing to do with summer effectiveness. After all, they are measured for their viscosity rating at 100cSt or the operating temperature of the engine, not the temperature of the atmosphere. And it is conditional on what the engine was designed for. A 20 weight, in a engine designed around that viscosity will do just fine in Death Valley in the summertime as a 40 weight will in an engine that was designed around that viscosity of oil. Keep in mind, whether the outside temp is 100F or 0F, the engine is still operating at 180F or whatever the design range is. And the design of the components and the temperature range of the engine itself, along with other factors determines the proper viscosity of oil by the OEM.

And generally, you would be correct about the "C" and "S" designations. But it is also interesting that some OEM's have specified "S" designated oil for their engines. The 2.8L inline 4 cylinder diesel in my 2006 Jeep Liberty, the manual specified "SF" rated oil. So things are not always as cut and dry as they seem.

Figured I would revive this thread a little and post the oil sample results on the Schaeffer 15w40 synthetic blend I have been using in my factory remanned Detroit 60. Pretty good sample results. Can't get the PDF of the oil sample reports to load up here, so am providing a link where I posted it elsewhere. I posted the first result there and if you scroll down a few posts, I have the PDF of three oil changes results.

Detroit 60 and Schaeffer 15w40 Synthetic blend | The #1 Trucking Industry Forum | The Truckers Forum

We sold some Shaffer oil back in the '90s for irrigation pump engines. Those engines sludged up worse than anything we have ever seen. So, I still won't use the stuff.

I've had my Cat on Delo Synthetic 5W40 for the last 125,000 miles with the OPS1 bypass filter and no oil changes. The last sample showed everything was ok, but the base is 4.33 so I'll be changing it when I get home. I think I'll go with the regular old Delo 15W40. At just 6 miles per gallon, I didn't get the really long extended drain I was hoping for with the OPS, so the dinosaur oil should get the same job done cheaper.

We started using bypass filters on our crop duster over 20 years ago. Went from 20 oil changes between 2000 hour overhauls to 2. Saved a boat load of money with no accelerated wear. If it works for a $30,000 air cooled dirty carbureted radial gas engine, it should be great for a modern computerized diesel engine too.

125,000 miles on the oil and Iron is at 120, Soot at 0.4% with 3.0% fuel dilution. Not too bad, I think.

There are anecdotal stories that one can claim about any oil. We have no clue what the conditions were that they occur and they are not in controlled lab settings, so we have no way of knowing it is the oil or the fault of maintenance, operation, or any number of external factors.

Now i used the Delo 5w40 synthetic and the 15w40 conventional in my Series 60 before I went to Schaeffer. I was getting a viscosity reduction in 15,000 miles. Both Delo oils, for some reason we could not determine, were shearing from a 40w down to the viscosity of the 30w. I have not had that issue with the Schaeffer. It all had me very perplexed, in that I have always had high regards for Chevron products. With the latest oil samples since I posted the previous stuff, I have almost doubled the OEM recommended drain interval and am not getting the viscosity loss. The Schaeffer is holding up great. Wear metals and such are no more at 25,000 miles on Schaeffer than they were at 15,000 miles on Delo. Doesn't make Delo a bad oil, just that my particular engine did not get along well with it.

Now, there is something here in all of this. Engines are like .22 rifles in a lot of ways. For instance, I can take a quality name brand ammo, say CCI, and shoot it out of two top quality rifles and one will shoot tighter groups than the other. Now I can switch to another brand of ammo, say Winchester, and the results will be the opposite! With the rifle shooting the best groups the first time around, now shooting the poorer groups. It is not the fault of the ammo or the rifles. It is just a matter of one rifle prefers one brand of ammo over another.

All major engine oils are good products. Each one brings something different to the party. But there is no one brand of oil that delivers the best results in all engines, every time, all the time. If one is not getting results they feel are good, then switch to another brand and try again.

As for the bypass thing, I am running bypass on my Series 60 also. But my comfort level is double the OEM recommended interval to extend the drains. That's it. Not wasting anything as it is what I am comfortable with. The oil does still show it is good for a while longer, but I am not, so it gets drained. I have no desire to compete with others on how long I can go on an oil change nor am I intimidated that I do not try. Each of us lives within our own comfort levels.

But as a side note to your comment, at 3% fuel dilution, that would be 30% over the Detroit Series 60 warning limit, so my skin would be falling off if I saw 3% fuel dilution. I would be making a bee line to the shop if it was at 2% to drop the oil. Each engine OEM has limits they set. Not sure where Cat sets the limits.