JJ's getting an education, YES AGAIN! ):h Over the past 7 months I have read numerous posts regarding diesel fuel quality and engine oil analysis. However, I never stopped to consider exactly what impact they might be having on my engine's longevity. :o: I buy fuel at truck stops assuming it was fine and replaced my oil/filter about every 4-5k miles. Truck runs great, but from what I'm reading I may need to do a better job of monitoring exactly what is going on inside my engine. :rolleyes:

So I'm doing some research and trying to understand the basics. From what I have read so far we may be understating, rather dramatically I might add, the importance of having regular diesel fuel and engine oil analysis performed on our trucks. :eek:

From what I have read so far the following affect engine oil analysis:

Engine manufacture
Oil brand
Mileage on the engine
Hours on the engine
Past abuse
Oil viscosity
Winter or summer driving
Driving habits
Oil sampling technique
Diesel fuel quality
Air filtration/contaminant removal
The link below explains how to read a diesel engine oil analysis report. I didn't realize so many different things were analyzed:

http://www.polarislabs1.com/pdf/HowToDieselFeulRep.pdf

If I'm interpreting what I have read correctly the engine oil can basically become like an acid and eat away at our internal engine components and dramatically reduce the longevity of the engine. :( The only way to know if this is happening is to analyze the oil to see what properties it has taken on while lubricating our engines. :confused:

I know there is much more to this than I understand and I'm likely way over my head with understanding exactly what I'm reading.:o: I suspect there are several other DP members in the same boat I am so I'm posting this in order to gather intel for myself and any others that might be interested. :rolleyes:

Those of you that are "in-the-know" about the importance of engine oil analysis please impart upon the rest of us the "in's and out's" or "do's and don'ts" of the importance of engine oil analysis, diesel fuel quality tips to include supplements, the best engine oils for engine longevity based upon documented engine oil analysis, etc. :ro)

No seat of the pants stuff here guys, just proven results based upon analysis results! Please use the KISS (keep it simple stupid) approach in responding. JJ :)

I can share with you guys what I know about diesel fuel.

All fuels are a mix of various other mixtures of hydrocarbons. They are blended (like scotch) to achieve a blend with specific desired properties. Everybody blends differently, and they're all trying to make a gallon as cheaply as possible within the constraints of their refinery.

ASTM D975 lists the specifications for US #2 diesel fuel.

Distillation:

The molecules that make up fuel have different boiling points. A fuel blend will start boiling at one temperature, and get hotter as the lighter components boil off. So, you get a curve...temperature vs. % boiled off. Water boils at 100C...from the first drop to the last. Fuels range in temperature from cooler to hotter as they are boiled down. There is a standard test, ASTM D86, that measures this curve. The 90% temperature is the temperature of the fuel after 90% has been boiled off. For #2 it has to be between 282 and 338C.

Flash point

Liquids don't burn. Vapors burn. When you see a pot of burning fuel, what's happening is the liquid is evaporating, and the fuel/air mix is burning. In order for vapor to burn, there is a range of mixtures (min and max vapor content) to support combustion. Diesel fuel at room temperature is too heavy (too non-volatile) to evaporate enough vapor to meet the minimum mixture to burn. If you heat up the liquid, more will vaporize, and at some point there will be enough vapor in the air to burn (if ignited). That temperature is called the flash point. You don't want a flammable mixture in your fuel tank, so diesel has a flash point spec of 52C (minumum..higher is ok). If your fuel has a low flash point, it probably got contaminated by gasoline. Gasoline has a very low flash point. In a gasoline tank, the mix is too rich to burn. It's in between (too rich and too lean) where you can get into trouble (i.e. have a flammable mix in the tank).

Sulfur

Currently there is a max spec for sulfur in on-road diesel fuel of 500 ppm (by weight, sulfur). The sulfur in fuel is actually chemically part of the fuel molecules. These molecules happen to have good lubricating properties. They also don't burn as easily. To remove the sulfur, you first convert it to H2S by reacting the fuel with hydrogen, then you separate the H2S by distillation. High sulfur fuels tend to smoke more, and produce more CO and unburnt hydrocarbons.

Sulfur also inhibits the platinum and palladium in cat convertors. Lower sulfur makes these catalysts more active. That's why next year we're going to 30 ppm sulfur.

API gravity

API gravity is just transformed density, but backwards. Higher gravity means lower density and vice versa. API gravity= 141.5/(specific gravity) - 131.5 Water has a specific gravity of 1, and an API gravity of 10. Lower gravity means more pounds per gallon and (usually) more energy per gallon.

Cetane number

Cetane number is an engine test. When the injector starts spraying fuel, there is a slight delay before it burns and the cylinder pressure rises sharply. the longer the delay, the sharper the rise (since more fuel is sprayed during a longer delay), and more noise results.

Hexadecane (a.k.a. cetane, a 16-carbon paraffin) is defined to have a cetane number of 100. Methyl-naphthalene is defined to have a cetane number of 0. They run a test engine and measure the ignition delay for blends of cetane and methyl-naphthalene. A fuel that has the same ignition delay as a 40% blend of cetane in methyl-naphthalene (by volume) is said to have a cetane number of 40. Higher is better.

Cetane number is a similar test to octane number, but the results are opposite. In gasoline you want resistance to spontaneous ignition. In diesel fuel, you want easy spontaneous ignition. Whatever molecule (or type of molecule) makes good gasoline makes bad diesel, and vice versa. Big molecules (of a given form) have lower octane, and higher cetane. That's why diesel is heavier...for better cetane number.

In the US, the minimum cetane number is 40. In Europe it's 50 and can be as high as 55 like in Sweden. Higher cetane is better, unlike gasoine where enough octane number is good, and higher is no better.

Cetane index

Cetane index is a poor-man's cetane number. The industry developed a correlation between cetane number and other fuel properties that are easy to measure...specifically D86 distillation and API gravity. There is a formula that relates cetane index to 3 distillation points and API gravity. The resulting number (cetane index) is an estimate of cetane number without having to do the engine test.

All fuels are spec'd by cetane number not cetane index. Cetane index will not reflect cetane-improver additives since they don't affect distillation or gravity...even though they increase measured cetane number. Plus, the correlation and CI equation may not work as well for desulfurized fuels, since they were developed for higher sulfur fuels.

Cloud point

Unfortunately, the molecules that are great diesel fuel (long straight chain paraffins) also tend to crystalize at low temperature to form wax. Harmless in and of itself, the wax can be filtered and plug the fuel filter. Cloud point is the temperature where these crystals start to form and the fuel turns cloudy. Below this point, they will start getting filtered and cause filter plugging. Once re-melted, they will no longer plug the filter, so there's no permanent damage. There are additives that will suppress the cloud point.

#1 diesel

#1 diesel fuel has less of the heavy molecules that form wax and become viscous at low temperature. It also has more aromatics for the same reason. The molecules that cause low temperature problems are the ones that are the best quality diesel (high cetane number, high energy, high density)...an unfortunate coincidence. Only run #1 if you have to to keep the fuel flowing in winter.

cit1991,

Thanks so very much for posting. While the info provided is obviously well within your frame of reference and technical knowledge/ability, I'm afraid it might be "too techie-fied" for the average smuck like ol' JJ here. Honestly I understood about half of that, alright smart-a$$es 1/4 of that, dangit 1/8th alright, get off my back! ):h Maybe the Jethro Clampett "3rd grade level" version would work best. :rolleyes:

As a quick add-on to your post I was surprised to read how diesel fuel changes its physical and fluid characteristics when temperatures rise and fall. Those of you that live in very cold climates should pay careful attention to the fuel filters in the extremely cold months. Turns out lots of sh_t happens between the fuel tank and "getting it burning". :rolleyes: Very interesting reading.

What I'm looking for is the "DP Bible" verses on if/when, how often, and any inside/out tidbits that the more experienced/knowledgeable guys can/will give us. JK, Cit1991, Landguy and others that "know their stuff" are great resources for us to go to school on.:ro)

Questions I have are: Should I do an oil analysis between oil changes, if so how often, and why?; Do certain types of oils perform better in colder weather whereas others perform better in warmer weather?; Where are the best places to have an analysis performed?; What aftermarket filters (air, fuel, oil???) produce the best analysis results? :confused:

I plan on keeping my truck for many, many years so engine longevity is my goal. I have 18k miles on my LLY already, if I'm doing any damage I want to stop it now. Later. JJ :)

JJ,

There is no "one size fits all" answer to your questions. There are too many variables to address in auto diesel applications. In addition, there is an element of "overkill" in many of the recommended oil change intervals due to these same variables.

However, if all you want is some good rules of thumb, here's my advice.

1- The advantages of performing oil analysis when you change your oil and filter will provide you with trending information from your first oil analysis. There are no absolute numbers. The same design engine will have different oil analysis, (OA), numbers depending on oil used, loading, ambient temp operation, engine temp operation, etc. You get the point. So, your oil analysis will only be useful for you to compare with the last sample.

Also, if you want to be anal on the OA, then you should also perform an OA on the virgin oil you use. This also has to be the same brand and formulation. The OA data may even vary from batch to batch of the same brand and type of oil. Due to Dino based oil stocks being a little different each time, there are some variables you will see on the OA. Synth oils will be more consistent due to being a more engineered product.

Even with oil analysis, you may not be able to predict when component failure will occur. Most of the time, it will confirm what you already know. Even if you did see pending failure, chances are that the dealership can't or won't do predictive parts replacement based on OA due to the current method of reimbursement from GM. If you did your own maintenance, you would see some benefit if your truck was used in mission critical applications.

So, with all of that behind us, and you still want to be super anal, here's what I recommend,

If you want to run Dino, use Mobil Delvac 1300 super or Shell Rotella. There are other good oils out there but, these 2 are easy to get just about anywhere and are good quality dino oils. Personally, I would change dino at 5000 - 7000 mile intervals.

If you want to run snyth, run Mobil Delvac 1. It has the best track record for synth. and is just my personal preference. Most of the synth oils out there are very good.

The advantages of synth over dino is that synth has a wider temp range of stability, meaning that you'll get better lubrication properties at low temps and high temps. In addition to temp stability, you will get increased additive package stability. But to realize this you have to extend you oil change interval out quite a ways. And if you extend your change interval you really should do some type of analysis. What I mean in extended oil change interval is on the order of 15,000 to 25,000 miles. You will have to change oil filters a couple of times during this type of interval due to the current filter schemes being used do not allow a stock full flow filter to adequately perform this long.

This price difference is pretty significant when comparing dino to synth.

For our trucks I'll use 3 gallons as a round number. You're looking at about $18.00 for dino to about $60.00 to $70.00 for 3 gallons of Delvac 1. About $40.00 for Shell Rotella snyth and probably about $50.00 for Amsoil. Other synth oils will be about the same.

Just staying with mobil products for the sake of comparison, you could do 3 dino changes for the cost of 1 synth change. From the economic side of things, unless you really need the added cold and hot lubrication properties, I don't think you will see any real extended longevity in using synth.

From the "overkill cause I can't control all the variables" side of things, if you load the engine with any regularity, (trailer pulling), and you don't want to sweat over how close to the margin you eating into on oil sheer breakdown, (hi ambient temps, pulling in the desert or a hot humid day in FL.), then go synth and change every 10,000 miles.

You certainly won't be wearing out the oil and you engine will be as happy as it's ever going to be.

There are many opinions to bypass filtration and oil analysis but IMHO, I just don't think you can control the variables involved enough to make all the added benefit payoff. However, it certainly won't hurt and it will give you something else to spend you money on.

I base this on the fact that under normal stresses the Duramax really has not had a lower end problem. I think what will get us all here will be injectors. And no one has been able to predict with any reliability when and how they are going to fail. That's why you see people with 2 and 3 filters on their fuel supply and bypass filtration on their oil supply and still poop injectors.

Do I think more filtration is better? You bet. Do I think that oil analysis is a good thing? Yes, if you use it for it's intended purposes and act on the information you attain. Just be sure you don't kid yourself into thinking that will protect you from all the evils of engine failure out there.

George Morrison makes his living selling lubricants and performing oil analysis and I'm sure if you PM him, he'll tell you the same thing.

He, unlike the rest of us, puts Delvac 1 in his truck and runs super clean BP Diesel Supreme from his own bulk tank and still got bit by the injector bug. He took all of the precautions anyone could have possibly done to increase the life of the Duramax and he still lost.

2- Oil Filters. I use Baldwin B1441. AC/Delco is great as well as WIX and Champion. In general, stay away from Fram and other cheap filters. I don't know of any oil filter tests that would show a dramatic difference between what I listed above. Any good quality filter will work as long as you change it regularly.

3- Air Filters, I'm not going near this one except to say I use OEM AC/Delco and I buy from Eric.

4 - Fuel filters. For the OEM, it doesn't matter what name is on it, they're all Racor built. For Secondary, that is a personal preference based on installation location, filter replacement availability and cost. They run anywhere from the Racor setup I have to John Kennedy's Mega Filter. Again, more filtration is better but it has not stopped injector failure.

Finally, here's my general rule for maintenance on anything. If you perform regular preventive maintenance on the vehicle you own, it will last longer than if you didn't. And if you flog your truck, it will not last as long as it would if you didn't. Once in a great while, there are exceptions to this rule, but not many...

DavesDMax, OUT-FREAKING' STANDING INTEL DUDE! :ro)

And written in language even ol' JJ can understand. This is exactly what I'm looking for. "Super Anal", YOU GOT ME PEGGED BABY! ):h

Now this is information I can use. Give me more boyz, MORE!!!!!!!! :muahaha:

What about the corrosive aspects the oil can attain? How does this happen, what should we be looking for? JJ:)

What about the corrosive aspects the oil can attain? How does this happen, what should we be looking for? JJ
Diesels don't really have the "corrosive" issues that gassers have. Cylinder blowby in a gasser will create acidic conditions and contamination in the oil. The big issues for the diesel are control of abrasive soot. In all engine lubrication situations, there are specific additive packages to meet these issues and you test/filter/change your oil based upon the the depletion of the additive packs. Changing your oil on a regular basis that is well short of its actual service life (5000 to 10000 for dino, 20000+ for synthetics) assures you that you have maintained the protection of the additives and are dumping before you reach an unacceptable soot or contamination level.

"Changing your oil on a regular basis that is well short of its actual service life (5000 to 10000 for dino, 20000+ for synthetics) assures you that you have maintained the protection of the additives and are dumping before you reach an unacceptable soot or contamination level."

Totally agree with Idle Chatter. The OEM recommended oil change frequencies have a safety margin built in due to the fact that it would be impossible to recommend one or two schedules for every driving condition. IMHO, the main advantage to oil analysis is trending wear metals and additive packages (as Daves Dmax states), and looking for contaminants, (mainly, dirt(silicone), coolant (glycol), diesel, soot level, and water ppm.).
I have a chart that GM produced quite a while ago, but don't know of its origin or its accuracy, but it shows the effects of filtration upon engine wear, and dont know how to post it either. I do know that on a diesel engine, particle counts are rather expensive due to the process of counting when soot is involved.
I think one of the most important things stated was to know your objective with oil analysis and acting upon it when needed. In order to extend oil drains and filter changes, oil analysis and a good understanding of the reports has to be a part of the decision making process, but it does come at a cost.

:thankyou2 for all the info! Awesome thread!!!:ro) I have been faithfully changing my oil and filter every 5K miles and fuel every 10K miles. I've been taking it to the dealer to have the servicing done so I have a hard record that all maintenence has been performed. But now after reading this, I feel I may need to do more in the analysis area because I plan on having this truck a long time.

Not to jack the thread, but any input on Caterpillar oil? I used to wrench at Cat Truck Engines and their oils seemed to really work well. The faithful PM drivers had some very well running and very clean engines. I'm sure good fuel had a lot to do with it too.

TIA!!!!

If soot is so bad one must ask why the EGR? Are guys finding much lower soot levels after installing the EGR blocker plate? Anyone have before/after engine oil analysis documenting results? OK, that's a lot of questions! But if soot is killing my engine it has got to go, at least what I have any control over. :mad: OK, is there more intel that needs to be on the table re oil analysis? :confused:

Now about those oil changes! I tow about 20% of the time, the rest is 50/50 combination of highway/city. Sounds like my truck is a better candidate for synthetics with E/O analysis and oil filter change every 7500 miles. Make sense? JJ :)

The EGR is for emissions control, not to extend the life of the engine. You'll have to talk to CARB if you think you're getting hosed.

Tinker with the EGR at your own risk. It is illegal don't you know.. .:rolleyes:

Run synth, change your filter at 7500, run a sample, and check again at 15,000.

OA will run you about $25.00-$95.00 per sample and type of analysis. Chuck in about $11.00 for a Mobil 1 Oil filter, and add about $10.00 to $12.00 for topping off the oil. Almost an oil change straight up. Particulate counts will cost you.

You see why I caution you about running OA's on auto diesels in non-commercial service.

Daves Dmax, so are you saying it is just as prudent to change the oil on a more regular basis regardless of running dyno or syn's as to perform O/A? In my case since I run the engine pretty hard when towing the 5ver I want the additional resiliance the synthetic oils offer. If I'm going to pay just as much to have the oil analyzed as to just change it out then "in with the new and out with the old"! ):h

I suspect the answer to my next question is in cit1991's post, I'm just not understanding it. :o:

I have read posts from JK, LanduytG and others speaking to the affect that air filtration has on their O/A reports. JK and LanduytG run Unifoam "oiled filters" and they continue to make the case for them with their O/A results. I have one as well that I took out after the Air Filtration Study was posted. I'm thinking of putting it back in if the O/A results are that much better. I cleaned it last night and my god that thing was FOS! I guess your supposed to use that whole can of cleaner on one cleaning because that is what it took. :(

Evidently the amount of air, or even moreso the quality of the air being introduced has an affect on the oil. I suspect it has something to do with cleaner combustion or less dirt/tar/gunky deposits in the oil, but as always I could be way off! ;) Can someone expound on why/how this happens? :rolleyes:

I also read that warmer weather can result in bacteria growing in the fuel tank and fuel filters, especially if water is present in the fuel. Is this not another reason to have O/A performed and if so how often? It appears that depending upon the area of the country you operate your truck within there will be different variables that determine how often to change the oil and filter and performing O/A. True? :confused:

Hopefully there are other guys like me that are "going to school" on this post. While I could afford to buy a truck like this I'm way over my head on the technical stuff, so I shoot for the maintenance items I can handle to improve longevity of the components. :grd:

Side note: In my next life I want to be a Lubrication Specialist like LanduytG! :cool: I like that title! ):h JJ :)

I change my oil when the GM oil life monitor hits about 50%. I do not do used oil analyses (UOA's). If I tried to run 15000+ miles on a batch of oil, then I might do it. Unfortunately, the UOA doesn't tell you much about the state of the filter, and changing oil really isn't that hard. On a $50,000 truck, 10 qts of synthetic oil and a filter is really not expensive enough to worry about. 15,000 miles would be about a year of drivingfor me, and that's too long anyway.

I like using the monitor because it debts me for idle time and cold engine time, and gives me credit for highway miles. It's much better than going by miles alone. I may choose not to go all they way until it thinks my oil is used up, but at least it's more rigorous than miles alone.

I use Mobil1 5W40. Either the truck and SUV stuff or Delvac1, whichever I can find.

I plan to change the fuel filter every other oil change. I know it's important, but I have yet to see any evidence that filtration is causing injector problems. Actually, there's evidence to the contrary. See

http://dieselplace.com/forum/showthread.php?t=24884&highlight=poll+injector

The results there tell me that secondary filtration has no effect on injector failure rates. True it's a non-scientific dataset, but it's better than nothing...and certainly does not indicate any advantage from secondary fuel filtration.

With regard to water and additives, I definitely would use the de-emulsify type. One, because it's what GM says to use, and why argue with the designers. And two, it makes sense to me. Water carries all kinds of garbage (metals and salts), and the last thing I want to do is make it easy for it to get through the filter. The filter will not remove anything dissolved in the emulsified water...only solids (not dissolved). The filter is there to separate water...let it do its job.

With regard to air filters, this says it all:


http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm

Keep in mind that 3" of water pressure drop is so small that a gust of wind can make that difference. The AC Delco has 2" more DP than the K&N. 1/2 of 1% more density to the turbo inlet, for the price of 18 times more dirt passing through? Not for my engine. Even the Amsoil filter passed 7 times more dirt.

On oil, you have to really have to watch the sneaky marketing guys. The part of the oil that does most of the lubricating is the base stock oil...that's the stuff they start with and add additives to.

Good dino oil (distilled and treated petroleum) gets separated from crude, then goes through several treatment steps...adding hydrogen, removing aromatics, and isomerizing. That last one is where the confusion starts. Isomerizing is a chemical reaction where some of the oil molecules are rearranged to make them better oil. The impurities are still there, but the base oil is better. If an oil has undergone this treatment, is can be referred to as a group III base oil.

Synthetic oil (in the old school sense) means you start with little molecules as pure chemicals. Then you combine them together is a specific way to make the ideal base oil. Then you add additives to this base oil to get the finished product. There are no impurities, and no undesirable molecules. Every part of it is engineered and custom made to be a good oil, and it's called group IV.

A few years back Castrol got tired of Mobil making all this money on synthetic motor oil. Some chemist (with very bad judgement) told the marketing department that their group III oil did in fact undergo a chemical reaction or two, which did technically make some of the molecules different than the starting dino juice....not ideally engineered, just different. They decided that distinction made group III oils "synthetic". And, out popped Castrol Syntec "synthetic" oil. Everybody else caught on and did the same.

Mobil got upset at the dilution of the synthetic label (a market they alone developed) and sued...and eventually lost.

You can now sell treated dino juice as synthetic if you treat it well enough...even if it's just refined petroleum.

Mobil (now ExxonMobil) continues to sell true synthetic oils with group IV base stocks and they even use group IV oils to dissolve the additives, so there's no dino oil in there.

That's why the specs for Mobil1 are different from the other "synthetics" ExxonMobil is the only major that produces group IV oils. Any other oil advertised with group IV base stock is probably using ExxonMobil base oil with their own additives.

Mobil1 is the only major oil using group IV oil..true synthetic. There may be a few other exotics in there too, but not many. Not Shell and not Chevron.

Any manufacturer that factory fills with synthetic uses Mobil1.

A few years ago, I had a pit pass and a credential medallion at the Indy500. Every garage along gasoline alley, without exception, and no matter how many Pennzoil, or Amsoil stickers were on the car...had plenty of the silver bottles with the big "1" on them in the garage.

So for the average smuck like myself it appears more prudent to just change the oil and filter more frequently, and those of us that really stress the oil such as for heavy towing or racing where very high stress levels are put on the oil it would be best to use a true synthetic like Mobil 1. JJ :)