Recent Oil Sample Results

Discussion in 'GM Diesel & DuraMax' started by Cowpie, Jan 5, 2014.

  1. Cowpie

    Cowpie Rockstar 3 Years 500 Posts

    This oil sample is not from a Dmax, but a Detroit Series 60. The engine has 200008 miles on it, and the oil had 13733 miles on it. This was the first run of Schaeffer 7000 15w40 synthetic blend CJ-4. The results show a very impressive add pack as part of the oil. According to Schaeffer, their 9000 5w40 full synthetic has the same add pack. I would have no problem putting this oil in a Dmax. I am going to stretch out the drain interval on the next run 3000 miles per their recommendation.

    View attachment Schaeffer 999 01.pdf
  2. Jason2325

    Jason2325 Rockstar

    I wouldn't run a syn in my diesel.

    There are two big disadvantages to synthetic motor oil that you will never hear mentioned by the folks selling the stuff. First is polymer shearing which is where the molecules of the oil that bond together to increase the viscosity of a multi-grade oil will come apart when they go through a very small aperture at pressure, as with the rod journals of an engine. Then the 5W40 oil can become a 5W at the point where it is most needed at 40W as in warm weather or under a load.

    Second problem is that with all diesel engines there is soot buildup in the motor oil and additives do not fix this, only oil changes remove it from the crankcase. Use of DEF for newer engines has greatly reduced the soot problem but not eliminated it. And anyone who deletes the DEF system has even more soot than an older engine going into the motor's oil.

    With heavy use or severe duty the oil change interval can be reduced by as much as 75%. With my truck's use I change the oil at 7500 miles though if I followed the DIC I would be doing it at around 13,000 miles. I do heavy hauling half of the time and so the oil life is shortened by 50% - roughly speaking.

    I could pay 2-3 times as much for a synthetic oil but I would still want to replace it at 7500 mile intervals. I would also need to find one that was 15W40 and not 5W40 for the areas where I drive. 5W40 is for subfreezing driving conditions which I encounter for less than a week out of the year. Much of my driving is with temperatures of 90 to 105 degrees and the correct oil to use is a 15W40 with the LML engines.

    If synthetic motor oils were advantageous all the big rig fleet operators would have switched years ago, but it is not and they have not. And the fleet operators are smart enough to appreciate the advantages of engines using DEF to minimize soot going into the crankcase and to know that in the long run it saves them money.
  3. Cowpie

    Cowpie Rockstar 3 Years 500 Posts

    Well, a little bit of something to stir the pot a little. The soot problem? My solution is bypass filtration. My soot levels are in 0.5 percent range over an entire OCI as compared to the OEM soot limit of 4%. As for the "big fleet" operators switching years ago, you would be correct. But that was years ago. Many fleets are now using synthetic blends as a minimum, with some using full synthetics. Trans Am, R.E. West, Jeff Foster Trucking, Sue Vinje Trucking, and the list goes on and on. The big mega fleets don't primarily because they rotate equipment before the warranty has even expired. Why spend more than you have to when you are going to dump the equipment back on the market and forget it?

    Fleet operators are concerned foremost with two things..... spreadsheets and profits. And the bare minimum to keep warranty compliant until dumping the equipment. They use the bare minimum oil that meets the OEM requirements and will get them by till the trucks are traded. Their motivation is considerably different than the individual owner.

    You state that with heavy use, oil change intervals will sometimes need to be reduced by up to 75%? Where did you pull that number from? How many oil samples did you run to determine that great of a reduction? And you must have a very terrible engine considering that many semi truck owners are extending drain intervals, on both conventional and synthetic oils, with very good results. Considering that the diesels in pickups are based on the same technology, just smaller, there is no reasonable explanation why the oil change intervals should be reduced even under heavy conditions. Only if oil sampling shows the oil is breaking down.

    Now, independent semi truck owners like myself, I regularly alternate between a Schaeffer synthetic blend in the summer and a Schaeffer full synthetic in the winter. I regularly tip the scales at near 80,000 lb yanking a 53' trailer. The oil can take quite a beating when yanking that much around up and down the hills. The OEM recommended drain interval for my Detroit Series 60 12.7L is 15,000 miles, but I use a CJ-4 oil that is also Detroit 93K218 compliant that allows me to extend to 22,500 mile OCI's with the OEM blessing. Now if a full synthetic isn't going to stand up as you contend, then my oil sample results from the lab are pure fiction, as they are some pretty darn good oil samples. And I have been running oil samples on equipment for a couple of decades now. And how do you explain that with even a 10w30 synthetic blend, Detroit engine with their current crop of EGR laden DD15 engines has an OEM recommended drain interval of.... 50,000 miles. Yep, I said 50,000 miles. No typo. And that is under full loadings of up to 80,000 lb, running nationwide including deserts, mountains, from the Rio Grande to the Arctic.

    And the little 2.8L diesel in my 2006 Jeep Liberty? It regularly gets 11,000 mile oil changes running 6.5 qts of full synthetic 5w40. And it has been known to frequently pull a 300 gallon fuel wagon thru crop fields.

    Are synthetic the cat's meow for everyone? Hardly. There are many good conventional oils out there. But synthetics do offer better resistance to breakdown in extreme heat, better flow in extreme cold, etc, and the additive package is usually a little stouter as well.

    And truth be told, the add pack is as critical as the oil. The add pack makes upwards of 25% or more of a quart of oil. I would take a conventional with a very strong add pack over a synthetic with a lousy add pack, but on the other hand, a synthetic with a very stout add pack is worthy of your dollars. You do get what you pay for. Most folks talk about conventional vs refined synthetics vs formulated synthetics, but they hardly ever take the time to see what the add pack of an oil is made of... it's strengths and weaknesses. You can learn a little bit about the add pack from the data sheets, but I find that sending in a virgin oil sample to a sampling lab can really be a great snapshot of what is in the oil

    Oh, and on that note, many like Lucas Oil Stabilizer. But the lab results on a virgin sample of LOS? Nothing more than a 185w base oil. No significant additives of any kind. No zinc, no moly, no detergents, nothing. Just an oil thickener. What a marketing scam.
    Last edited: Jul 10, 2014

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