Buster, they are probably multi-grade because they only have to hold the engine together for one race.
10W vs 10W-30 vs SAE 30 cylinder wear
- Thread starter G-MAN
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G-MAN, why do you think then that most racing oils are multi-grade such as M1R? Or, are most racing oils VII free? I can only think of RL that uses straight grade. And then you have Eneos with their 0w-50? Obviously VII's.
I never totally bought into the notion that Mobil 1 Racing that was sold at retail is the same Mobil 1 actually used in racing.
I think modern racing formulas, especially in Formula 1, are low viscosity oils that are blended with either (1) no VI improvers, or (2) blended with exotic shear stable VI improvers that if used to formulate the typical OTC syn PCMO the price would be $50 per quart.
In what's marked on page 121 of this study, the visc. of the VII is given at 100c (534 cSt) along with the base oil's (10.85 cSt). For the tests data given where the VII was mixed with the base oil at 18%, I calculated out the 100c visc. to be something like 105 cSt!
Thanks.
If I was understanding some of the technical aspects properly, doesn't those diagrams then actually show just how too much VII can make the film thickness dangerously thin by "trying too hard" so to speak to keep the viscosity at the proper range?
That paper is pretty much beyond my meager ability tribology wise, but I think that I got the "gist" of it. Someone correct me if I'm wrong...
That paper is pretty much beyond my meager ability tribology wise, but I think that I got the "gist" of it. Someone correct me if I'm wrong...
Curious Kid, on a percentage based calculation, I also got a blended viscosity of 105 cst. But that's not how the viscosity should be calculated. I don't know if we can use a viscosity calculator (assuming that the VII is an oil) or whether something different from that is even necessary (assuming the VII does not act like an oil when blended with the base oil). Bruce may know.
But however it goes, that study is an eye-opener to the uninitiated. In the graphs (at those high shear rates), the blended oil gave thinner film thicknesses than the base oil alone. Of course, the blended oil has higher Kinematic Viscosity at 100C than the base oil alone. It again shows the viscosity dependence on shear rate. More completely, viscosity is a function of temperature, pressure, and shear rate. Different parts of engines put different amounts of temperatures, pressures, and shear rates on oils so it's really a wild thing going on with the oil in it. Even just a set of piston rings goes from very high shear rate during mid-stroke and zero shear rate for the instants at top and bottom dead centers. Pressures in journal bearings can be enormous and quadruple the viscosity of the oil relative to what it would be at that same temperature and shear rate but at atmospheric pressure.
But however it goes, that study is an eye-opener to the uninitiated. In the graphs (at those high shear rates), the blended oil gave thinner film thicknesses than the base oil alone. Of course, the blended oil has higher Kinematic Viscosity at 100C than the base oil alone. It again shows the viscosity dependence on shear rate. More completely, viscosity is a function of temperature, pressure, and shear rate. Different parts of engines put different amounts of temperatures, pressures, and shear rates on oils so it's really a wild thing going on with the oil in it. Even just a set of piston rings goes from very high shear rate during mid-stroke and zero shear rate for the instants at top and bottom dead centers. Pressures in journal bearings can be enormous and quadruple the viscosity of the oil relative to what it would be at that same temperature and shear rate but at atmospheric pressure.
A lot (of weird things) going on is right. A fascinating reality that is lubrication, which is an eye opener as I'm coming at this from the angle of curious bystander/user/consumer.
With the visc. figure above, I'm wondering just how thin a base oil could be, but like JAG had alluded to, finding viscosity with the addition of VII's to an oil is likely beyond percentage calculations...it still provides a spark of wonder.
Take care.
With the visc. figure above, I'm wondering just how thin a base oil could be, but like JAG had alluded to, finding viscosity with the addition of VII's to an oil is likely beyond percentage calculations...it still provides a spark of wonder.
Take care.
But.... doe's staright 30w have detergency in it? I had used quaker state 30 staright weight many yearss ago, when i was 19/20, in a 1985 Isuzu hatchback. If anyting, it wa harder to crank the engine over, but overall never had a problem, other than feeling the engine have to work a litle harder.
Some do, some don't. I can go over to Murrays and they have Valvoline SAE 30 non detergent, and right next to it is the SAE 30 SL rated stuff and SL definitely has detergent. Just check the bottle. If it's non-detergent, it should say so.
Originally Posted By: G-MAN
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More data here: 1st slide of Page 6. Effect of viscosity on shear strain rate. The 30 wt oil is nearly Newtonian while the 20W-50, having polymers, is a psudoplastic Non-Newtonian fluid. In this chart, above some shear rate, the 30 wt. is more viscous than the 20W-50. Take this as an example, NOT a universal trend with all straight 30 wts and all 20W-50 oils.
Here's the slide:
As the slide depicts, it would appear that conventional wisdom, that going to higher running weight to provide "ultimate" protection appears largely false as long as the base oil is lower than one's previously used running weight oil grade. Just how does the ration of protection vs. operating efficiency play out compared to running a straight weight that appears to offer better film protection? Fluid film vs. mixed-film/boundary lubrication regimens - which by another graphic that I don't have access to at the moment, shows lower friction losses even though it works upon reactive product on the surface, which IIRC leads to minute amounts of base metal removal from the load bearing surface materials as these reactive films wear away. It appears like it's efficiency vs. protection?
I am also pondering just how to now take an HTHS number, as it's likely to be listed as being higher with the 20w-50, but yet in the slide, it doesn't hold up like single weights - take the 30wt for example in the slide. I'm not sure as for what areas really see such shear strain to deem this very important.
Take care.
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More data here: 1st slide of Page 6. Effect of viscosity on shear strain rate. The 30 wt oil is nearly Newtonian while the 20W-50, having polymers, is a psudoplastic Non-Newtonian fluid. In this chart, above some shear rate, the 30 wt. is more viscous than the 20W-50. Take this as an example, NOT a universal trend with all straight 30 wts and all 20W-50 oils.
Here's the slide:
As the slide depicts, it would appear that conventional wisdom, that going to higher running weight to provide "ultimate" protection appears largely false as long as the base oil is lower than one's previously used running weight oil grade. Just how does the ration of protection vs. operating efficiency play out compared to running a straight weight that appears to offer better film protection? Fluid film vs. mixed-film/boundary lubrication regimens - which by another graphic that I don't have access to at the moment, shows lower friction losses even though it works upon reactive product on the surface, which IIRC leads to minute amounts of base metal removal from the load bearing surface materials as these reactive films wear away. It appears like it's efficiency vs. protection?
I am also pondering just how to now take an HTHS number, as it's likely to be listed as being higher with the 20w-50, but yet in the slide, it doesn't hold up like single weights - take the 30wt for example in the slide. I'm not sure as for what areas really see such shear strain to deem this very important.
Take care.
As long as the oil will flow dureing start up and is not so thick as to spin a bearing all is good! Too many people worry too much about 5W VS 0W VS 10W etc........In most cases none of these people that get their panties in a twist over this even need much lower then 10W30 for their ambient temp.'s!!!! Common sense should tell you not to run 20W50 on your trip to Canada for Christmas dinner like wise it should equaly tell someone in California or AZ,FL or NC that they do not need a 0W30 to survive winter!!!!
Another thing is that people forgett that with equal additive packages an oil withthe better HTHS always win's in the end....The problem is that no one makes a 5W20 and a 10W40,5W40 with identical base stock Group percentages and identical additive packages for comparison etc So often we do not see the results we expect because the additive packages are so different.THis is why a lot of SAE test's use special formulated oils with one being a reference oil and the rest haveing identical additive packages so that HTHS and viscosity can be evaluated for it's effects on the test engine! I think it is no accident that most additized oils on the shelf are 5W20's becuase their base stock alone can not cut it!
Another thing is that people forgett that with equal additive packages an oil withthe better HTHS always win's in the end....The problem is that no one makes a 5W20 and a 10W40,5W40 with identical base stock Group percentages and identical additive packages for comparison etc So often we do not see the results we expect because the additive packages are so different.THis is why a lot of SAE test's use special formulated oils with one being a reference oil and the rest haveing identical additive packages so that HTHS and viscosity can be evaluated for it's effects on the test engine! I think it is no accident that most additized oils on the shelf are 5W20's becuase their base stock alone can not cut it!
Originally Posted By: JohnBrowning
I think it is no accident that most additized oils on the shelf are 5W20's becuase their base stock alone can not cut it!
I must have missed that post. Where or when was it determined that 5w20 oils are more additized than other weights?
I think it is no accident that most additized oils on the shelf are 5W20's becuase their base stock alone can not cut it!
I must have missed that post. Where or when was it determined that 5w20 oils are more additized than other weights?
Originally Posted By: flatlandtacoma
Originally Posted By: JohnBrowning
I think it is no accident that most additized oils on the shelf are 5W20's becuase their base stock alone can not cut it!
I must have missed that post. Where or when was it determined that 5w20 oils are more additized than other weights?
JB's statement doesn't make any sense. Typically a 5w20 and 5w30 will use the same or nearly the same base oil blend.
Originally Posted By: JohnBrowning
I think it is no accident that most additized oils on the shelf are 5W20's becuase their base stock alone can not cut it!
I must have missed that post. Where or when was it determined that 5w20 oils are more additized than other weights?
JB's statement doesn't make any sense. Typically a 5w20 and 5w30 will use the same or nearly the same base oil blend.
This has been a very eye-opening thread for me. Being a younger guy, I'd just assumed that multiweight oils were superior for the most part. Still, being an ACVW guy, I've been a little distrustful of VIIs and have picked oils with relatively low VIs.
I do have a question though -- what effect do PPDs have on the film strength? I would assume that they don't lubricate as well as oil molecules...
- Scott
I do have a question though -- what effect do PPDs have on the film strength? I would assume that they don't lubricate as well as oil molecules...
- Scott
I've been through 5 motors in the GN. Two had synthetic 15-50 and three had Sureflow 20-50 dino or straight 60 dino. Without fail, the synthetic filled motors looked like they had suffered a severe lack of lube on the cylinders and pistons. Pistons were nearly frozen on the pins. The straight 60 weight and 20-50 still had the hone marks when torn apart. I've always followed a <1,000 mile OCI no matter what oil was in it. I've never had an explanation for this but after reading this thread it's making me wonder.
I was just wondering, after all this talk about the potential merits of a straight SAE 30 oil due to its VII-free construction and inherent shear stable design, it seems as though it's an excellent choice for many people during seasons that do not dip into the extreme cold temperatures.
But, how does a high quality SAE 30 oil (such as Amsoil ACD HDEO SAE 30 for example) compare to an equally high quality, fully synthetic 0W30 such as Amsoil's Signature Series (SSO)? The SSO has a HTHS value of 3.2, and likely has a lower amount of VII's than nearly all conventional 5W30 or 10W30 oils. The SSO is supposedly a very shear stable formulation, even moreso than the TSO that it replaced.
So, for the same reasons that an SAE 30 is likely a good oil choice (since no VII's and high shear stability), shouldn't the performance of a highly shear stable and low VII 0W30 be nearly as good, if not equal to any good SAE 30?
Just curious! Thanks
But, how does a high quality SAE 30 oil (such as Amsoil ACD HDEO SAE 30 for example) compare to an equally high quality, fully synthetic 0W30 such as Amsoil's Signature Series (SSO)? The SSO has a HTHS value of 3.2, and likely has a lower amount of VII's than nearly all conventional 5W30 or 10W30 oils. The SSO is supposedly a very shear stable formulation, even moreso than the TSO that it replaced.
So, for the same reasons that an SAE 30 is likely a good oil choice (since no VII's and high shear stability), shouldn't the performance of a highly shear stable and low VII 0W30 be nearly as good, if not equal to any good SAE 30?
Just curious! Thanks
That was mentioned earlier, that a Group IV/V 10W30 with no VIIs could give you all the benefits of a straight-weight along with low-temp pumpability. All else being equal.
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Multi-grade oils were originally promoted as a year round oil for people who didn’t know enough to change grades with the seasons; and for that they have served their purpose. If you look at marine engines, they are subject to the most severe service. Marine use is the equivalent of driving your car all day at 90 MPH pulling a 5000lb Trailer. Mercruiser Owners manuals warn against using multi-grade oils at any time, and say you can use 20W50 in an emergency. Single grade 30 or 40 weight oils are specified; a 25W40 is also been specified by some manufactures. (Actually a 25W40 would be a great oil for automobiles, although it is costly.) Even though marine engine coolant temps are low (to keep overall engine temps down due to fire hazards) the engine oil temps do run hot. Multi grade oils would break down very quickly.
A straight weight oil probably makes sense for automobile summer use, although I see very little problems with engines using any oils today. Most cars go to the scrap yard with rusted out bodies, a broken tranny, or other needed repairs that the owners refuses to pay for.
A straight weight oil probably makes sense for automobile summer use, although I see very little problems with engines using any oils today. Most cars go to the scrap yard with rusted out bodies, a broken tranny, or other needed repairs that the owners refuses to pay for.
Here is an interesting article by someone who knows what they are talking about from the BMWCCA web site:
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Thanks.
Thanks for working with us on this; please feel free to repost in compliance with the rule. EKP
ADMIN NOTE: Please review Forum Rule #6. We can't allow the posting of whole copyrighted items, as was done here, as it can potentially expose the board to liability for a CR violation. You are welcome to post excerpts, a link to the article, or both; but again, not the whole thing. Paraphrasing key portions as a supplement to links and partial quotes is also OK.
Here is G-Man's well stated interpretation of the rule:
Quote:
Just a reminder that posting copyrighted material in its entirety on BITOG is not permitted.
If you find something interesting on CNN, for example, you may post a link to it. But DO NOT copy and paste the material into your post unless you have permission from the copyright holder to do so.
Posting brief quotations from copyrighted material is okay and falls within the Fair Use provisions of US copyright law.
Thanks.
Thanks for working with us on this; please feel free to repost in compliance with the rule. EKP
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