Moly in Engine Oils

Not open for further replies.
Dec 4, 2002
SF/Bay Area, CA
I offer this as food for thought. It's not completely correct as a couple of the Schaeffer moly-containing oils are listed on the API site as approved for at least the SJ service level ( they meet API SL at any time?). Anyway, take a look and comment as you see fit. "Check out the OEM bulletin from Cummins. It is the Cummins Engine Oil Recommendations, Bulletin No. 3810340-02 dated May 1996. Its probably best if you stopped by a Cummins Dealer and purchased this bulletin- about $2 or $3. On page 7 it has a section on FRICTION MODIFIERS states: "There is firm evidence that certain friction modifiers, molybdenum dithiophosphate for example, can in certain formulations result in cam follower pin failure at relatively low mileage"........ From years working with engine test programs to approve engine oil formulations for API licensing, we can tell you that NO engine oil containing Molybdenum additives has been certified by the full range of engine tests necessary to gain API approval. Molybdenum compounds in motor oils can degrade and cause bearing corrosion and is particularly aggressive towards copper. In almost all cases, any engine oil formula having "moly" will also contain a Copper Deactivator which will protect bearings from the moly compounds. The only problem, the copper deactivator decomposes at relatively low temperatures and looses it's potency after a few thousand miles." Source -
We have discussed this previously (search on "moly dithiophosphates"). This company is using scare tactics and word associations to sell their own product(s). Moly Dithiophosphates are not used in modern oil formulations, and no self respecting oil company or blender would use them. Moly dithiocarbamates, yes! [ December 06, 2002, 09:49 PM: Message edited by: MolaKule ]
look what these people say about sysnthetics: "When you compare synthetic basestocks with mineral basestocks, you'll find that synthetic basestocks have a better viscosity index, temperature range, oxidation rate and volatility. However, synthetic basestocks fall short in film strength and lubricity". Is this true? Rick
The last sentence is false. Full synthetic bases have an average of 5 times the film strength of petroleum bases.
I'm loving this board already! Definitely some significant brainpower on it relative to lubricants. I'm especially intrigued by MolaKule's comment about moly dithiophosphates and Bob's article on the Cummins tests run at SwRI. Bob, can you or have you published a PDF file of the Cummins report you mentioned?
I must tell you how quickly I could dispel the propaganda. First clue was the organo-sulf (thio) phosphate form of Mo, but most important was the wheezy jizz about synthetic oil. Joe Sixpack stand no chance I tell you - Joe Sixpack never tried I guess....I have the answer: Government regulation [Happy] [Dummy!]
Being the skeptic that I am, I'm always asking questions from multiple sources until I get an answer that makes sense to me. Cummins has supplied an approval letter on the Schaeffer oil but their Customer Support is sending out mixed messages. Bob, you may wish to offer some guidance to the party at the bottom of the attached: Summary: gen moly oil add'tv quest Solution: Thank you for your email. Yes, we have found that moly additives can be aggressive to copper; moreover, we have identified no need for oil additives, Then also, if you have a need for more elaboration, we say, "why do you ask?" We thank you for your interest in Cummins products. Please let us know if you need assistance in locating the nearest Cummins-authorized Dealer or Distributor Service Provider. For assistance in locating a Service Provider, feel free to use Cummins North America Dealer Locator, which can be found on Cummins website: This site can be found on the "Service Locator" link, at Cummins "North America" website: For service locations and Cummins Regional Offices, outside North America, you may select the region of the world in which you have an interest, by using the following Cummins website and click on the "view distributor network" button: Please let us know if you have other questions and if away from your computer or have a time-critical request that needs more urgent attention, feel free to call us toll-free (from North America) at 1-800-DIESELS (343-7357). Customers may also call Cummins switchboard 1-812-377-5000 (worldwide toll call) and ask for the "800-DIESELS Call Center" for assistance. Cummins Email (via webpage): Email direct: [email protected] Regards, -- Powermaster Customer Assistance Center Cummins, Inc. Columbus, Indiana, USA
From the Mobil papers I have read, anything less than 100 ppm of wear metals seems to be low in their context.
"Summary: gen moly oil add'tv quest Solution: Thank you for your email. Yes, we have found that moly additives can be aggressive to copper; moreover, we have identified no need for oil additives, Then also, if you have a need for more elaboration, we say, "why do you ask?" Yes, but which Moly additives??? [Frown] Are they going by old data?
Molekule, A level of 100 ppm may be fine when it comes to iron levels in an oil analysis, but a level of 42 ppm of lead from simple corrosion is quite high. I would expect a conventional 15w-40 diesel oil without moly like Delo 400 or Delvac 1300 to do much better than 42 ppm in this particular test. You will note that the Supreme 7000, which is 30% PAO, did much better. So I'd just stick with the Supreme 7000, 15w-40 for a diesel application, having seen this data from a controlled test. TooSlick
I guess I missed something, but it would take a lot of corrosion to arrive at >40 ppm of lead. Secondly, how do they attribute this corrosion to a moly additive and by what mechanism?
Yes, Edit: Same moly compound, same ZDDP, one oil has POA (#700, which passed), the other (the one without the POA, the MB X-200, which passed). I suspect the higher corrosion of the MB X-200 was due to the detergent/dispersant package (which provides the base chemicals for acid neualization), or the higher sulfur content of the MB's base oil, and not the moly. BTW, 42/120 = approx. 35% of the amount of lead corrosion allowed. So where's the beef? [ December 09, 2002, 03:39 PM: Message edited by: MolaKule ]
Molekule, Standardized tests are set up so that even cheap petroleum oils with minimal additive chemistries pass them. I feel that any premium oil should exceed these minimum test standards by a wide margin.... I think the Supreme 7000 did better because the PAO basestock is much more resistant to oxidation/nitration and it ended up with a significantly higher EOT TBN ....that'd be my guess. TooSlick
Here are the tests that an oil must pass to meet CES 20076: Mack T-8E, T-9 Caterpillar 1K, 1P ASTM D5966-96 RFWT Cummins M11 (300 hours) Seq IIIE, vis incr @ 64 hr, max 100% ASTM RR:D02-1379 EOAT Corrosion Bench Test ASTM D4684 Gel Index, 12 max ASTM D5800 (Noack), 18% max XW40 Sulfated Ash, max 1.85% The Corrosion Bench Test is but one test that the oil (or more importantly, the combined additive package/base oil mix) has to pass. Beware of the simplicity of focusing in on the results of one simple bench test versus understanding the complete battery of tests an oil must undergo. For your reference:
TooSlick, I dunno, it has about 23% PAO on the average, might affect oxidation; probably affects low-temp pumpability more than high-temp oxidation. I am still leaning more toward the different additive packages, less the PAO influence. You make a point though; PAO IS part of the additive package. So how much better or how much less lead do you think the MB X-200 should show? What oils do we have to compare? This might be interesting. Anyway, the point I originally addressed was that it cannot be the moly that is causing the increased lead corrosion, because of the same type of moly treatment in each.
Not open for further replies.