HTHS VS Flow... after reading Oil by AE...

[Kitto]

http://63.240.161.99/motoroil/index.html
I am confused right now...
If flow and thickness is important to choise an engine oil... why German car always look at HTHS for better protection... 3.5 or more and have A3...
to get the high HTHS, a 40 weight oil is usually require...
so when chosing oil... should I look at the weight more or flow more...

and a real case is 40 weight oil have correct cold start valve tick problem of my Mazda Miata and my friend's Miata... we have this problem when using 30 weight oil...
should I look at flow more or weight more... hence a higher HTHS for better protection??

 

[boxcartommie22]

i see it this way what good is an oil no matter how thin if it shears down..i would say use an oil with a high ht/hs..redline is a great example.. if you want to use an excellent ht/hs ratio in their thin oil 5w20 redline is a way to go.

 

[Ron AKA]

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i see it this way what good is an oil no matter how thin if it shears down..i would say use an oil with a high ht/hs..redline is a great example.. if you want to use an excellent ht/hs ratio in their thin oil 5w20 redline is a way to go.

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I would agree. You may however want to check and see how thin Red Line 5w20 is at low temps, and also realize that the higher HT/HS will cost you a bit of HP and mileage.

 

[JohnBrowning]

Shear,viscosity and flow are all different charteristics of an oil and they are not directly linked to one another. The base stock and VII's used has a huge impact on all of the above charteristics. You can find 5W30's that have an HTHS of 3.5 or higher and you can also find them with HTHS as low as 2.9. You need to think in a less linear fashion when thinking about oils charteristics and how one charteristic affects another.

Proir to a new lead matrices(sp)that Honda developed that makes lead based bearings something like 200 times tougher then traditional babit bearings HTHS was critical to rod bearing life!!!! Main bearings were also affected but not as much as the rod bearings. Since Honda's discovery it has become much easier to have long bearing life with low HTHS oils.Not everyone is useing this technology yet. You will also see that some companies are increaseing the pan capacity and adding piston oilers as well as they make the switch to 5W20's. Car valvetrains in the last 15 years have made a lot of changes that make the valvetrain easier on oil. Since much better materials are being used for the valve springs they were able to lower the spring pressure without fear of early fatigue. This puts less stress on cam followers and camshaft. Many car companies use rollorized valve trains. This reduces the shearing forces that the oil is forced to operate under.Most camshafts have very gradual and progressive profiles so as not to load the valvetrain to quickly. So in most modern engines the valve train is a pussycat and is mostly looking for the additives to do their job.

Based on old research an HTHS of 2.9 was the bare minimum for long engine life with 2.6 causeing grossly accelerated wear inthe bearings and valvetrain. An HTHS of 3.3-3.6(can not rember the exact number) proved to be the ideal comprimise in terms of protection v.s. viscosity. AS you went past these the increase in protection quickly started to level off and fuel consuption quickly started to increase. Now with all of this said we do not have any modern tests with these new bearing materials on modern engine designs!

 

[cfromc]

Thank you JohnBrowning!! I found your one post much more informative than the numerous times I've seen this:

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...realize that the higher HT/HS will cost you a bit of HP and mileage.

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[1sttruck]

"If flow and thickness is important to choise an engine oil... why German car always look at HTHS for better protection... 3.5 or more and have A3...
to get the high HTHS, a 40 weight oil is usually require..."

When tavelling places with her friend in Germany thislast summer my wife said that they were often crusing around 120 mph. This was just a middle aged housewife driving normally, which will depend in part on the vehicle being used. In Spain when the BMW 750 bike was tapped out on the highway at about 125mph I still had to scoot over for the fast traffic.

Flow also needs to be considered with respect to operating conditions.

 

[427Z06]

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...Flow also needs to be considered with respect to operating conditions.

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in concert with engine design as John Browning so eloquently highlighted.

 

[Ron AKA]

John, you have some interesting theories, but would suggest they may stretch reality a bit. Some things to consider:

Flow and standard viscosity are directly related. Every engineering formula to calulate flow uses viscosity, and flow resistance. If you know those two you can calculate flow. To my knowledge HT/HS is not a standard viscosity measurement and is not used to calculate flow.

Babbit bearings need to be soft, but not too soft, and resistant to fatigue. For that reason lead is often used but the fatigue properties are bad. Higher quality babbitt will not have any lead at all and may use quite a bit of silver. I don't think the new thin oils have much to do with the babbitt used in bearings. The trick is to run on oil, not babbitt. Perhaps Honda have found a way to prevent the fatigue in using lead, and they have now been able to go to a cheaper lead based babbitt. Suspect this is for cost not durability.

I agree with your thoughts on the valve train. They are areas of extreme pressure and that is being reduced by design. 4 valves per cylinder for example greatly reduced the reciprocating weight.

Research in the late 90's was indicating the need for higher HT/HS but it has been later found that down to 2.6 is not a problem at all. Generaly piston and bearing losses improve with lower HT/HS and valve train get worse. This basically happens on old engines and new engines.

http://www.iantaylor.org.uk/papers/IMechEFE2000.pdf

 

[JohnBrowning]

Ron, I never said that HTHS is a measure of viscosity! What do you think in my post is stretching reality? I ask because what I presented is mostly what I have learned from SAE papers that have either been posted on this site over the years or linked to on other sites or read and printed while I worked for GM.GM has access to the entire SAE library. These are not my idea's although I did over simplify a few things for the sake of bandwidth. Silver is not in the bearings as an alloying material at all as far as I am aware. The silver you speak of is usualy plated to the bearing on commercial diesels so that they can tell wich bearings are wearing.On a large commercial diesel it is not uncommon to service just the rod bearings or just one sleeve etc....Most companies are trying to get away from lead and are useing Aluminum bearings more and more often. Now do not be mislead as even Aluminum bearings will still have heavy metals in them either some lead or some cadnium along with other alloying metals.The problem with aluminum is that it has poor embedability as compared to a premium babitt like bearing.The faster they can get away from lead and candium the better in many compaies opions as they represent more environmental cost's long term.

What research is their that shows that rod and main bearings live a long healthy life at HTHS values of 2.6? I am not doubting you but I have never seen it on this site or any other and would love to read it.

I am looking forward to your reply-Thanks John

 

[Curious Kid]

In thought, I would think that an oil with a high VI would be more likely to yield higher HTHS results over a like weight rated oil whose VI was lower. Also because of the range in actual visc. within classified weight ratings, there's another potential for dissimilarity. It's like comparing M1's 0w30 to Castrol's 0w30 (GC). Heck, try a multi 30wt vs. a straight 30wt.

The remark about using increased quantities of VII to have a base oil make the grade is of some concern, for they take up volume that could otherwise be used for other critical additives or base oil. Shearing may be an issue, as in the case of the rate of shear ocurring more quickly than the rate of oxidative thickening which would result in a lowering of tested viscosity. Lastly, excess amounts of VII shear material could add to sludge festering potential - w/ extended OCI and overloading of detergents/dispersents. I'd imagin it not something normally encountered by the average road-going engine in a good state of tune, but than again who am I to know. I'm here to learn!

Viscosity as I see it is more exacting of an oil's property, especially as it's given with temp. at which measured.

If the oil in question meets manufacturer's specs and you use the vehicle as it was for the most part intended, than I wouldn't worry so much about using it. That's the beauty of test certifications!

Weight as in 20/30/40, is a less accurate reference of an oil's characteristics because it's less exacting, but still acceptable I feel due to the not-so-critical nature of an automobile engine. For a lot of city going drivers that drive but a few miles, the oil's likely to never reach full operating temp as I'm lead to believe in my readings here and from watching my vehicle's guages. Wt. ratings are a generalization for the lay person, not oil fanatics

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Flow as I understand it is a property that is related to an oil's weight, or more specifically to it's viscosity. If of higher viscosity than it is more resistant to flow or in being displaced, and less resistant if of lower viscosity.

There's directly and indirectly related properties...like cause and effect, and for which there are many a variable!

 

[427Z06]

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Flow and standard viscosity are directly related. Every engineering formula to calulate flow uses viscosity, and flow resistance. If you know those two you can calculate flow. To my knowledge HT/HS is not a standard viscosity measurement and is not used to calculate flow.

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HTHS is a viscosity measurement given in cP under specified conditions.

 

[Ron AKA]

Check this link out for typical industrial bearing materials. #2 Babbitt, is the pretty much the industry standard. Lead based babbitts are typically only used in lighter loaded slow speed machines.

Yes, silver may be more a specialized use. Check the next link as well. Using aluminum is ugly. That's a Briggs and Stratton trick to cut cost - make the casting your bearing. Not a particularly good material to make bearings from.

http://www.purityalloys.com/Babbitt Bearing Alloys.HTM

http://www.silverinstitute.org/uses.php#bearings

On durability of engines using HT/HS oils, you don't have to look any further than this forum. See the used oil analysis for 5w20 oils. Most of them that are SM Starburst will have a HT/HS at or near 2.6.

 

[427Z06]

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Using aluminum is ugly. That's a Briggs and Stratton trick to cut cost - make the casting your bearing. Not a particularly good material to make bearings from.

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Aluminum alloy bearings are used in more engines today than any other type of bearing material.

 

[Curious Kid]

In viewing AE Haas's oil data on the first link above, I guess I stand correctted about the M1-GC HTHS relationship - unless it's a new formulated change from when I last looked into GC's specs, I could have sworn it had an HTHS of 3.5 or something while M1 was 2.9...Like everything else, things change!

 

[bruce381]

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Flow and standard viscosity are directly related. Every engineering formula to calulate flow uses viscosity, and flow resistance. If you know those two you can calculate flow. To my knowledge HT/HS is not a standard viscosity measurement and is not used to calculate flow.

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HTHS is a viscosity measurement given in cP under specified conditions.

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Correct no more no less

bruce

 

[Ron AKA]

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Using aluminum is ugly. That's a Briggs and Stratton trick to cut cost - make the casting your bearing. Not a particularly good material to make bearings from.

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Aluminum alloy bearings are used in more engines today than any other type of bearing material.

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That does not make me feel good. We do need good oils if that is all we have to work with.

 

[Ron AKA]

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In viewing AE Haas's oil data on the first link above, I guess I stand correctted about the M1-GC HTHS relationship - unless it's a new formulated change from when I last looked into GC's specs, I could have sworn it had an HTHS of 3.5 or something while M1 was 2.9...Like everything else, things change!

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The Castrol 0w30 sold in Canada is made in Germany (green), and according to the Canadian website has a HT/HS of 2.9. However, I don't know what you can really conclude from this however as Castrol post useless specs. What they are really posting is the minimum and they are correct it is 2.9 for a 30 wt.

http://www.castrol.com/liveassets/bp_int...wnloads/t/t.pdf

 

[Ken2]

AE Haas has some very unusual theories. He is not a mechanical engineer. His theories are his alone, and not shared in industry.

Basically, the oil needs the film strength to keep the parts separated. Other things equal, higher viscosity oil has higher film strength. Kinematic viscosity, measured in centistokes, is the time oil takes to flow through an orifice, and that is not the best measure of the actual viscosity of oil when stressed. HTHS is a better measure. In the future we may see kinematic viscosity no longer used, but in the meantime, that is the system we have for determining 20 wt, 30 wt, etc.

The force trying to push the parts together is measured as pressure. Either bigger bearing surfaces are needed to handle the load or oil with higher film strength is needed. This is especially important in oscillating or sliding surfaces that don't build a hydrodynamic wedge of oil like a rotating journal in a sleeve bearing does and actually lift the journal away from the bearing.

I do not buy into AE Haas' theories. Lower viscosity oil does flow better, but does not provide the film strength nor thickness of the oil film, other things equal. I choose the viscosity the engine maker chose and top quality oil of high HTHS.


Ken

 

[1sttruck]

"On durability of engines using HT/HS oils, you don't have to look any further than this forum. See the used oil analysis for 5w20 oils. Most of them that are SM Starburst will have a HT/HS at or near 2.6."

Which also reinforces why you can't ignore operating conditions, and along with extended drains and engine design is why thin oils aren't used as often in Europe. It's almost a moot point if you're using thin oils in a high performance car in the US, as you can't get the daily high speed use in a large population of users like you can in places in Europe.

 

[JohnBrowning]

Ron AKA, I was not refering to UOA I was wanting actual research like an SAE Published paper or something like that! UOA would not hold up as research their is no control and little repeatability.THe ball park numbers I tossed out are on this site someplace under an HTHS thread. They actualy weighted the bearings and other wear parts prior to instalation in the engine then weighted them after the test. They repeated this over and over again to come up with the results.You might try reading up on modern bearing designs as well. Aluminum bearings used in mains and rods are not cast they are produced in much the same way as a babitt bearing the difference is that Aluminum is the main ingredient instead of lead. Traditonal babit bearing is lead tin and copper. If I rember things right the steel is copper plated then nickle or silver plated then the babitt is applied then it is plated again with silver.Aluminum bearing are used in Lexus V8's and seeing how they use Titanium rods ballanced to .003 of a gram of each other, sodium filled valve, forged crankshaft etc.... they would not try to save a penny by useing a cheap bearing.I am sure you are thinking like the bearing journals for the camshaft in OHC engines wich is cast and machined in place usualy with really high silicone content as well in that area.Those can be recast and remachines as well. In some cases theiris enough material on the cap side to remove a little and simply remachine.