AEHaas criteria and Visc. Specs

[ericthepig]

(Had this question in another thread, but it was apparently falling off the radar - it received no comments/answers. Thus throwing it back out in its own thread. Editing the original for clarity.)

Question on AEHass criteria for pre-op temp protection -

You can read the spec of an oil and see the visc. at 40degC, 100degC and (cold pump visc.) -30degC. So I'm thinking the 40degC level is key to wear protection per AEHaas' criteria as defined in his oil visc. article (for the majority of Americans for the majority of the year) - ie, having good flow during first 20-30 minute of op. But is visc. at 40degC indicative of flow just under that temp, and then on up to 100degC. One of my attractions to Schaeffers 7000 5w30 is the (for me unheard of) visc at 40degC of 47-52 cSt. I've perused many a PDS, and I ain't never not seen 40degC visc anywhere near that for a 5w30. If I've discerned this correctly, then Schaeffers 7000 5w30 is a trump card in pre-op temp protection. Plse advise if my thinking is muddled or troubled.

BTW, guys in Houston TX today (and Little Rock AR (100degF w/ 110 heat index expected today)) are thinking flow at pre-op temp doesn't apply to them (at least not today). But if I'm reading Haas' article correctly - the issue still applies. A bottom line I (trust I) understood from Haas article is - an does NOT lubricate properly till it's at op temp (multiple chemical and physical reasons why this is the case). To put it bluntly, if it's 110degF outside and you start your engine, your oil is not working lubricating properly.

So, back to the question - is the visc at 40degC a good indicator of pre-op temp protection for the majority of Americans for the majority of the year?

Thanks!

 

[Eddie]

I think that two points best determine the cold oil viscosity and therefore the wear resistance. The two viscosities being that at the pour point(-40C) & at +40 C. There have been articles written that plots cylinder wear vs oil temp. I I can remember where I saw the articles I will post them. Ed

 

[Steve S]

Quote:

---

I think that two points best determine the cold oil viscosity and therefore the wear resistance. The two viscosities being that at the pour point(-40C) & at +40 C. There have been articles written that plots cylinder wear vs oil temp. I I can remember where I saw the articles I will post them. Ed

---

Are those tests done with additized oil or unadditized oil And is there a comparison as a baseline . Remember when cold the pistons are not round the clearances are different, there is only so much additive Plating " the heat activated prosess continues as a cycle when the engine is running.

 

[Steve S]

The only cold start that is worth worrying about is for example a straight 30 wt used in 0 degree weather .get a real thick milkshake . suck it up througha straw. It takes a long time to reach your mouth ,your engine is running with out oil for a long time. Now suck up some of the milk shake after it reaches room temperature .The time it takes to reach your mouth is almost instant' Lubrication .Normal?cold start wear isn't worth worrying about.

 

[Blue99]

Keep in mind that 40C is 104F degrees and probably more accurately reflects an oil sump temperature obtained during the first 5 minutes of drive time than an actual start-up oil temperature.

Most late model vehicles spec'd for 5W-20 or 5w30 are seeing cold start-up viscosities of around 100 cSt during the typical 3 months of summer and 65-75 start-up temps.

If the majority of factory engines fare just fine at 100 cSt for start-up, why obsess about the 40C oil sump temp some minutes into the warm-up?

Also, keep in mind that the high rpm cars driven by AE Haas probably see 4K rpm just backing out of the driveway!

 

[RI_RS4]

Quote:

---

Keep in mind that 40C is 104F degrees and probably more accurately reflects an oil sump temperature obtained during the first 5 minutes of drive time than an actual start-up oil temperature.

Most late model vehicles spec'd for 5W-20 or 5w30 are seeing cold start-up viscosities of around 100 cSt during the typical 3 months of summer and 65-75 start-up temps.

If the majority of factory engines fare just fine at 100 cSt for start-up, why obsess about the 40C oil sump temp some minutes into the warm-up?

Also, keep in mind that the high rpm cars driven by AE Haas probably see 4K rpm just backing out of the driveway!

---

Blue, I agree. I think DrHass has taken an SAE paper out of context and extrapolated one minor result, that was not fully reported on, to create a "criteria".

If startup/warmup wear was so sensitive to 40C viscosity, we would be able to correlate cylinder and ring wear to higher 40C viscosity in UOAs. If someone can show me that feature in the data, I might be convinced. However, it would be difficult to filter out all the other variables, since we can see very large differences in wear due to oil and additive formulation, even within the same grades.

 

[JAG]

Why do so many people think those writings are anything but a plastic surgeon's thoughts? It drives me nuts.

 

[Gary Allan]

Well, the good doctor is no slouch ..but I too don't necessarily agree with his thin oil theory in terms of wear prevention. Surely it can (probably) reduce some initial start rate (as in height on a graph) of the 20 minute wear curve ..and can SURELY reduce parasitic loses....

..but...the main component to cylinder ring wear is lack of thermal saturation where the ill fitting parts aren't fully expanded. This is the 20 minute gauntlet that every engine runs. You don't see Audi/VW showing 50% MORE engine life just because they're at opt oil temp in 9 miles instead of 16 (or 9 minutes instead of 20) due to their heat exchangers. The oil is thin and warm. The engine isn't.

You can thin and pre-warm oil and coolant ...but you can't simulate 2000F combustion temps to expand the materials.

Again, one disputed point from the writings shouldn't be used to discount its entire worth. Many of the inferences are right..but perhaps for one or two questionable/challenged reasons.

 

[ericthepig]

Interesting - I was of the thinking that Haas' article and it's hypothesis were categorically accepted by the sages of BITOG. To now see otherwise knocks me back to Baltic Avenue on the Monoply board of my understanding of oil and wear.

In my present thinking, Haas' opinions are withstanding - they make good sense. But the issue appears to be multivariate as Gary Allan pointed out. Also, another knowledgeable BITOGr recently said the thick/thin debate is still a debate - which caused me pause.

 

[moribundman]

Quote:

---

the sages of BITOG

---

That right there is funny -- no insult intended.

As for thin oil and "wear prevention" in high-powered sports cars that are mainly driven in stop-and-go traffic or used for cruising, it's just nothing that interests me at all. I'm more interested in wear minimization in cars that are driven as intended.

 

[JAG]

Gary, you hit on one major point and did it well.
There are also other things in the writings that are just plain wrong. Just as importantly, there are many important aspects of lubrication that were not taken into account. I give him credit for researching and writing, but my problem with the writings is that they've been posted online in many places and many people read them thinking they are the writings of an expert in tribology. They can cause people to make bad choices. They also give people a false sense of knowledge. To his credit, I wouldn't trust any one person in the world to write what he tried to write ("General Theory of Engine Oil" ...yeah I made that name up). Tribology is so complicated that no one person can know enough to make such broad statements. Also to his credit he has learned a lot of good info from recent study of tribology literature as shown in the recent threads he made that are in the Tech forum. They show some of the errors in the conclusions he made in the earlier writings. Dr. Haas, if you are reading, I mean no offense by saying these things. I'm not putting myself above you either. I've written things too that I later realized need correction.

 

[Steve S]

Some people love K@N air filters,