Why Do Knowledgeable Folks on Here use 20 wt Oil

[ZeeOSix]

Sorry I learned alll about this in engineering school. Its for sliding surfaces (including bearings ) as noted.
I won't convince and neither am I trying to . I have always known it as 3 factor curve. But yea.

A better name for the Stribeck Curve would be the "Lubrication Regimes" curve.

FYI ... the Petroff's equation you referenced is a simplified Sommerfeld number type of equation and is very limited to the bearing being perfectly concentric, which they never are. Using the Sommerfeld number is the right way to analyze and design journal bearings. The Sommerfeld equations take into account the load, MOFT, and other parameters of operating journal bearings. Journal bearings run in full hydrodynamic lubrication, unless the MOFT is zero due to factors that can make it zero. So they are on the right end of the x-axis on the Stribeck Curve.

https://www.engineersedge.com/calculators/petroffs_hydrodynamic_lubrication_15764.htm

Sommerfeld number, S

 

[ZeeOSix]

For actual racing, yeah, why run thicker than necessary? If anything the rule is to prevent people from going down in viscosity for extra power at the cost of quicker engine rebuilds.

How do you know what's "thicker than necessary" without doing a whole test program on the race car, which would be routine engine tear downs, inspections and measurements. The race rule focused on the oil viscosity used should say the thinnest oil you can run is the manufacture's oil cap spec, but if people want to run a thicker oil to help protect the engine better, then why not let them if indeed they don't get a race advantage with 0.2 HP more with thinner oil.

 

[userfriendly]

How do you know what's "thicker than necessary" without doing a whole test program on the race car, which would be routine engine tear downs, inspections and measurements. The race rule focused on the oil viscosity used should say the thinnest oil you can run is the manufacture's oil cap spec, but if people want to run a thicker oil to help protect the engine better then why not let them if indeed they don't get a race advantage with 0.2 HP more with thinner oil.

The oil has to be thicker than necessary, because if it was thinner than necessary once, the engine would squeak to a stop.

 

[scrllock]

How do you know what's "thicker than necessary" without doing a whole test program on the race car, which would be routine engine tear downs, inspections and measurements. The race rule focused on the oil viscosity used should say the thinnest oil you can run is the manufacture's oil cap spec, but if people want to run a thicker oil to help protect the engine better, then why not let them if indeed they don't get a race advantage with 0.2 HP more with thinner oil.

If the numbers are higher on the bottle than what's allowed by the rules it seems like you don't need a test program.

 

[ZeeOSix]

If the numbers are higher on the bottle than what's allowed by the rules it seems like you don't need a test program.

Well, there ya go ... yes, I don't need a test program to know that higher viscosity will result in more film thickness between moving parts, which means more wear protection - especially on a car pushed hard on a track or similar use conditions. It's the simplest aspect of how lubrication works. I would however need a test program to try and figure out what the thinnest oil I could use in those conditions and still have full engine protection. The simplest way to go is run a thicker oil for such use conditions.

 

[scrllock]

Well, there ya go ... yes, I don't need a test program to know that higher viscosity will result in more film thickness between moving parts, which means more wear protection. It's the simplest aspect of how lubrication works.

ok. do you have any links to that supra that tore down their engine after a track day?

 

[ZeeOSix]

ok. do you have any links to that supra that tore down their engine after a track day?

It wasn't the Supra talked about in this thread. It was an old video, believe it was YTer "savagegeese". You really think that every car that specs xW-20 for the street is going to have the same engine protection during a full blown track session running at near max HP all the time with the same xW-20 oil at much higher oil temperatures? Why do you think car manufacturers like Ford, GM, etc say to use thicker oil for track use?

 

[scrllock]

It wasn't the Supra talked about in this thread. It was an old video, believe it was YTer "savagegeese". You really think that every car that specs xW-20 for the street is going to have the same engine protection on a full blown track session with the same xW-20 oil?

huh? are you arguing about something? I never said that.

 

[ZeeOSix]

huh? are you arguing about something? I never said that.

You seem to be questioning why someone would ever use thicker oil. Do you think running the oil cap viscosity for track use is not going to cause any added wear vs running a thicker oil?

 

[scrllock]

You seem to be questioning why someone would ever use thicker oil. Do you think running the oil cap viscosity for track use is going to not cause any added wear vs running a thicker oil?

did you read the context for that comment? he is racing in a series that requires a specific viscosity. racing is different than track days.

 

[ZeeOSix]

did you read the context for that comment? he is racing in a series that requires a specific viscosity. racing is different than track days.

Per your post 304, so you're saying they can't run higher than the oil cap, or can they ... ? There's not any engine HP advantage running a thicker oil, so why would the rules knee-cap someone if they wanted more engine protection.

"racing is different than track days" ... are they also limited to an RPM max, lol. Pushing an engine to the limits is pushing an engine to the limits.

 

[scrllock]

Per your post 304, so you're saying they can't run higher than the oil cap, or can they ... ? There's not any engine HP advantage running a thicker oil, so why would the rules knee-cap someone if they wanted more engine protection.

"racing is different than track days" ... are they also limited to an RPM max, lol. Pushing an engine to the limits is pushing an engine to the limits.

no idea man, take it up with the friend of the guy who's in this series. if you want to tell him he should break the rules that's your imperative.

 

[ZeeOSix]

no idea man, take it up with the friend of the guy who's in this series. if you want to tell him he should break the rules that's your imperative.

I'm just trying to get clarification from your statement about the oil viscosity rules. Maybe they should make it a rule that everyone has to run a grade or two below the oil cap viscosity, and can't add an oil cooler.

 

[userfriendly]

I'm just trying to get clarification from your statement about the oil viscosity rules. Maybe they should make it a rule that everyone has to run a grade or two below the oil cap viscosity, and can't add an oil cooler.

The notion of an engine oil viscosity rule is absurd.
“We won’t know who the winner is until the UOA lab results arrive a month from now.”

 

[ZeeOSix]

The notion of an engine oil viscosity rule is absurd.

Agree ... the only rule that would be logical would be that you couldn't run a viscosity less than the oil cap viscosity, as that could give a slight HP advantage. If someone theoretically can lose HP running a thicker oil, then that should be their choice since it would actually give them a slight disadvantage with respect the HP. If they limit what viscosity can be used, then they should also allow an added oil cooler if someone chooses to do so.

 

[ltslimjim]

A friend of mine tracks his Fit. Champcar endurance series. I'm sure they are using a 40 grade but I'll find out....

EDIT: they run M1 5W30 for this...however, for some racing series they run the recommended 0W20! In that series rule state you have to run what the manufacturer calls for so what's on the cap is what they run. Would anyone know? Of course not but rules are rules.

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These cars are really fun to drive; especially modded but even if not it’s a sporty suspension. Cool they go up a grade most of the time. I do wonder what their oil temps get up to compared to the stock 160ish.

 

[factorytuned2012]

Why are so many fascinated by the use of 0W-20

 

[Al]

Very nice. Kind of tell you why the thinner CAFE mandated oil cannot protect as well under transient conditions...but I digress.

 

[userfriendly]

Why are so many fascinated by the use of 0W-20

Virtue signalling.

 

[Glenda W.]

Why are so many fascinated by the use of 0W-20

Human nature, like watching a train wreck…