Is high HTHS still important for a normal vehicle?

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I get you dude, really...

For my VW car I track? I run the oil based on what VW recommends which is a 502 so be definition will have the higher HTHS. I'd have no issue running a 502 5W30 as well. Would I run a 20W? Not in that car. What if I had a GTI calling for 508/0W20? For daily use sure, for track use, I'd do the 40W b/c yes, I want all the HTHS I can get when I'm pushign 270 oil temps and beating the snot out of it. That extra head room means zero (to me) driving a car around town...everyone here want to think they are severe-duty all the time when in fact, v. few are and the thinner oils are just fine in those use-cases. Run what you want clearly and if having that headroom makes you feel better, by all means! The data/science shows you have more protection.

I have considererd just running 5W30 in it b/c our Lexus uses the same oil so would be easier....but again...not necessary/doesn't make one bit of difference that anyone can measure/tell here in an econo car with 150hp driving my a 20 year old. Funny as it is tuned for a bit better driveability and maybe a few stray hp (NA car...tunes don't do much but give you a bit more agressive timing maps to take advantage of 93) and he is likely going to start auto crossing it...still...the 20W is just fine in that case.
The VW 502 standard is a really strong requirement. Which brand/type 5W-30 do you use which meets that VW 502.
 
HTHS > Fuel economy any day of the week. I am willing to take a 0.5%-3% drop in overall fuel economy if it means my engine stays protected.

I am not a fan of CAFE standards. Example is my mom's Rav4, uses 0W20 but it is under warranty so I am stuck. Good reports on 0w20 oils but I need my peace of mind. Once warranty is done, I will bump the oil up to a 0W30 or a 5W30.
In some carmaker pdf it's around 1% savings , not worth to play russian roulette.
 
The VW 502 standard is a really strong requirement. Which brand/type 5W-30 do you use which meets that VW 502.
I don't use a 5W30 that is 502 - I use 5W40s in my 3x VWs (see signature). Liquimoly makes one as does Castrol and now it looks like M1 all 5W30s that meet VW502 00 amongst other approvals.
 
I get you dude, really...
Dude? You getting spun up? ... seems like it. 😋

For my VW car I track? I run the oil based on what VW recommends which is a 502 so be definition will have the higher HTHS. I'd have no issue running a 502 5W30 as well. Would I run a 20W? Not in that car. What if I had a GTI calling for 508/0W20? For daily use sure, for track use, I'd do the 40W b/c yes, I want all the HTHS I can get when I'm pushign 270 oil temps and beating the snot out of it. That extra head room means zero (to me) driving a car around town...everyone here want to think they are severe-duty all the time when in fact, v. few are and the thinner oils are just fine in those use-cases. Run what you want clearly and if having that headroom makes you feel better, by all means! The data/science shows you have more protection.
Yes, the controlled testing shows more viscosity gives added wear protection ... that will never change as long as two moving parts are separated by a film of oil. The extra headroom may not matter to you, but it does to me (to cover all possible street driving conditions) and many others, so yes we will point out why that headroom may matter. I could care less if someone runs WD-40 in their engine, but doesn't stop me from pointing out the Tribology facts about the relationship between viscosity/HTHS/MOFT and wear.

Obviously, anyone knowing anything about Tribology wouldn't run a xW-20 or less on the track unless they have some crazy big oil coolers installed. Or they plan on rebuilding their engine quite often like real racers do.
 
I wonder why people are willing to take risk with thin oil.
Can't afford gasoline? Then change the v8 truck for car with small 3/4cyl engine. Or get LPG.
 
Dude? You getting spun up? ... seems like it. 😋
You keep repeating yourself and yes, I get all of it so I guess makes me "spun up?" You may be the king of getting the last word on BITOG which is backed by 35K posts.
Yes, the controlled testing shows more viscosity gives added wear protection ... that will never change as long as two moving parts are separated by a film of oil. The extra headroom may not matter to you, but it does to me and many others so yes we will point out why that headroom may matter. I could care less if someone runs WD-40 in their engine, but doesn't stop me from pointing out the Tribology facts about the relationship between viscosity/HTHS/MOFT and wear.
Yes/agree.
Obviously, anyone knowing anything about Tribology wouldn't run a xW-20 or less on the track unless they has some crazy big oil coolers installed. Or they plan on rebuilding their engine quite often like real racers do.
I'd wager there are a quite a few GR Supras on the track running 0W20 - next track event I'll collect some data b/c there are always several, will be interesting to find out what they are using!
 
I wonder why people are willing to take risk with thin oil.
Can't afford gasoline? Then change the v8 truck for car with small 3/4cyl engine. Or get LPG.
All this risk and all these cars on the road running whatever oil they call for so call that "thin" for this dicussion and I don't hear about the prolific amount of engines with excessive wear and grenading.
 
I'd wager there are a quite a few GR Supras on the track running 0W20 - next track event I'll collect some data b/c there are always several, will be interesting to find out what they are using!
And exactly what is their oil cooler design situation? Take the oil coolers off and try running them on full on track use. We all know it boils down to controlling oil temperature to control the oil viscosity under use.
 
In some carmaker pdf it's around 1% savings , not worth to play russian roulette.
I meticulosly calculate my fuel economy for my 4 vehicles with an excel spreadsheet for the last 10 years.
When I switched from 5W-20 to 5W-30, I saw no measurable difference in fuel economy.

It's helpful to not discuss oils in terms on xW-XX viscosity, but instead to think in terms of HTHS.
To me, using an oil with a HTHS of 2.6 is borderline protection,
as during the oil change interval, the oil will shear and become thinner.

As per the HTHS wear graph that ZeeOSix posted earlier in this thread, once the 0W-20's HTHS goes below 2.6, wear exponentially rises, especially on the piston rings.
 
All hail the mighty Zee0Six!
You can't point it out, can you ... back peddling, lol. I'm waiting to see where you claim I basically didn't say the same thing about thinner oil and long term wear.
 
All this risk and all these cars on the road running whatever oil they call for so call that "thin" for this dicussion and I don't hear about the prolific amount of engines with excessive wear and grenading.
Here we go with the "grenading" and 1000s of dead cars on the side of the road spin, lol. Who said thinner oil would cause "excessive" wear? All that's been said is that thinner oil can cause more wear, especially when the HTSH gets below 2.5-2.6 cP for some engine components. And depending on all the other factors involved that cause engine wear, when many factors line up the wrong way there certainly could be excessive wear. Context and terminology matters in these discussions.
 
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You can't point it out, can you ... back peddling, lol. I'm waiting to see where you claim I basically didn't say the same thing about thinner oil and long term wear.
All we need now is for AEHaus to join the discussion and muddy the waters by making his claims about thin oils LOL.
 
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