15W30 revisited

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There was a story behind the creation of 15W40. I think it originated from truckers mixing 10W30 and SAE 50 together to obtain a shear-stable multi-grade HTHS 4.4. I was playing with SAE 20 and 15W40 on an ASTM blending chart, and found that mixing the two resulted in a blend that looked like 15W30. The two engine oils were: Duron 15W40 40C 118 100C 15.6 150C 4.3 Duron SAE 20 40C 65 100C 9.1 150C 2.7 Low/High 45/55%
 

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There are several ways to arrive at 15W30. The above maintains base oil integrity at the expense of a lower W or higher VI. The MIT paper linked in the "Dislike for 20W50" thread cleared up some of my concerns. Figure 3.4 and 3.5 on pages 24 and 25 addresses one of them: Boundary friction at ring reversal. The other is this quote later on in the paper: "Failure due to excessive wear is ONLY (mine) at the maximum (wear) point and not at the surrounding area". The maximum wear point in the discussion was at the ring reversal point, but that quote could apply to all engine parts. My strategy with the blend is to avoid un-necessary low W and VI numbers to eliminate that variable. The viscosity curve after 120C was mentioned in the paper, but not discussed to my satisfaction. My intuition tells me that at 120C and above, mono-grade lubricants out perform multi-grade lubricants, especially those that contain VIIs. Anyone who has taken apart an engine will observe the cross-hatch intact from 90 degrees to BDC. All the cylinder wear is at the top ring reversal point and it tapers off from that point downward.
 
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Agree with your premise...particularly as one of your recipe hasn't got VII in it. Have you considered using their 10W (aka 10W16 now that 16 is a grade) ? 1/3 10W, 2/3 15W40 would be 3.5 HTHS, close to 15W. Dang, you've made me want to start blending again.
 

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The MIT paper got me thinking that the higher SAE mono-grades have more VI between 120C and 180C than the lighter grades have. It would be interesting to have a high temperature VI for the application of HTHS instead of just 40C to 100C. When comparing SAE 10W to SAE 20, the specification that I looked at was the flash point. The SAE 20 being much higher at 231C, suggesting a better resistance to heat than 10W. For the application of HTHS at the ring reversal point, I believe that the higher the flash point the better. Temporary shear at the ring reversal point I think is undesirable as the lubricant is reduced to it's base-oil viscosity. By blending SAE 20 instead of a reduced percentage of 10W with 15W40 plays into the notion that a higher base-oil viscosity is better. We still have the VII in the 15W40, but that grade has proven to be hard to beat, and there is no point in throwing the baby out with the bath water. I don't want permanent shear at the end of the oil's service life to go below what a 0W40 would, taking the history of that grade into account. The stay in grade bar had to be raised to make 0W40 work, and if I remember correctly, it was you who posted the link 12 or 13 years ago. To raise the HTHS to 3.7-3.9 blending SAE 30 with 15W40 is an option that results in a 15W40 that plays at the low-end of the SAE 40 scale.
 
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All good logic, and I'm tending to agree. Since my post yesterday, this thread has come up. which has the API reference 20W30 as VII free (and presumably dino),which makes me think that an SAE 20 from today is probably more like a 15W20 rather than the odd sounding 20W20.
 

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The 15W designation was likely achieved by Chevron blending R7 group 3 with SAE 30 until the grade is met. We are stuck with blending two existing products. If we throw out the need for 15W and go with 20W30, the experiment becomes interesting. Blending SAE 40 and 25% 5W20 synthetic, will achieve 12.49 with a HTHS of almost 3.9. If that blend stays in grade, 20W30 and 15W30 makes 15W40 obsolete. Does the HTHS have to be redundantly high with VII containing engine oils to satisfy the requirements of the piston ring reversal point when temporary shear is present?
 
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Taking the HTHS of the originals, and putting them through the VII calculator is the usual technique.
 
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Originally Posted By: used_0il
Does the HTHS have to be redundantly high with VII containing engine oils to satisfy the requirements of the piston ring reversal point when temporary shear is present?
Old old thread that may have some pertinence here. http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/1029053/1 Although it has got me wondering if that's the premise for the ultra high VI 0W20s that seem to be designed with overly high KV100s for their HTHS (lots of shear)....maybe they are trying to have different operational viscosities, KV in the reversal point, HTHS in the high shear cylinder zone. If so, I still think they'll be barrier coating mid stoke sooner rather than later.
 

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The molten salt additive test used 20W30 without FM/VII and Mobil-1 5W30 (FF) for base-line oils. Then the MIT project tested the affect of a ceramic heat barrier on the outside of a cylinder liner in a diesel engine with a 9.5 inch stroke. In the interesting articles section, the problems with testing and funding for GF-6 and PC-11. All in search for the one-size-fits-all engine oil for ambient and application. "Wear challenged engine oils" in the face of falling oil prices. Gotta love it.
 

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This oil has been available for almost a year now. Has anyone tried it or used the UOA program? Will this oil become the first of many 15W30s to come, perhaps picking up some automotive manufactures' gasoline and Diesel certifications along the way?
 
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Originally Posted By: used_0il
This oil has been available for almost a year now. Has anyone tried it or used the UOA program? Will this oil become the first of many 15W30s to come, perhaps picking up some automotive manufactures' gasoline and Diesel certifications along the way?
I was anxious to try the 15W30 last year, but had a long wait for availability. There were big posters on the walls of some truckstops advertising the oil and free oil samples but the oil wasn't in stock (at least when I was looking for it). When I bought my 2013 Volvo and found the oil temp was regulated at 245-246F (~118C), I chickened out on the 30 grade. I recently found myself persuaded to try Delvac Elite 10W30 and while I cringe a little from the oil pressure readings, I have gotten over the fear of a 30 in my engine. I say all that to indicate I may indeed go on and try the Delo 15W30. If I do, I will take virgin, used and a mid oci sample. That was my plan last year, but If all goes well I may just stick with 10W30 year round.
 
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Originally Posted By: used_0il
This oil has been available for almost a year now. Has anyone tried it or used the UOA program? Will this oil become the first of many 15W30s to come, perhaps picking up some automotive manufactures' gasoline and Diesel certifications along the way?
Just for fun, I'll speculate on the latter part of your post. I'm going to guess that the Delo will remain the only one of it's kind, at least actually using the 15W30 "severe duty" moniker. With the demands for increased fuel economy and lower emissions regulations, it seems that 10W30 is quickly becoming the new standard that 15W40 has been for so long, with 5W20 possibly replacing 5W30 (for top fuel economy) in the not too distant future. As long as we're allowed to run remanufactured engines, 15W40 will still be a hot item, but going forward with XW-30 and later XW-20 oils, I think 15W30 will get blown away with low sales. As a counter to everything I wrote above, maybe 15W30 will become extremely popular because of it's price point. It will probably be the lowest priced XW-30 due to it's conventional makeup and if it gains manufacturer approvals, maybe it'll be considered the best mix of fuel economy and good return on investment. I still think it'll be the former of my post rather than the latter, but this was just for fun; I'm not an oil industry analyst.
 
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I don't think 15w30 will make much of a dent in the commercial truck market. Reason is that all heavy truck OEM's are factory filling with 10w30 and recommending it. There is a lot of CJ-4 10w30 around. 15w30 might get a niche following, but will not ever become much of a fleet choice, especially those that are not regional only operations. Fleets are not into playing the neat little oil viscosity games that get done at sites like this. If the OEM recommends a 10w30, that is what is going in the truck. It will be tough enough to get many fleet shop supervisors off of 15w40. 5w40 has hardly made a dent in fleet choices. An obscure blend like 15w30 hasn't got much of a chance except in smaller regional operations.
 
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Originally Posted By: Shannow
Taking the HTHS of the originals, and putting them through the VII calculator is the usual technique.
I messed up here, as Cp and Cst are only equivalent at the density of water. Need to convert them to Cp, which is the measure for HTHS, and for the cold pumping performance. So need to add density into the equation, which is usually on the PDS, and a correction from 15C to 150C which is the 0.895 factor that A Harman has calculated. So HTHS of a monograde should, and trawl through enough Product Data Sheets be Widman KV100 * density on the PDS * 0.895. Back to the 15W30, here's another that is in my region... http://www4.total.fr/asia-oceania/singap...hure%202011.pdf Has a 15W30 "economy" oil, and a 20W30 for hotter climates.
 
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