Higher viscosity = higher operating temps?

[aquariuscsm]

Originally Posted by MetalSlug
Made me want go back 0w20 instead of 5w30 on my i4 Honda Accord 2011


I'm going back to 10W30 in my Accord.

 

[ChrisD46]

*I would also like to think - if say Hyundai/ Kia as example list owners manual approved oils as 5W20 , 5W30 and 10W30 (depending on ambient temps) then there is a bit of leeway in acceptable ouils based on key engine tolerances (albeit not as much as for the Mustang Coyote 5.0L).
Originally Posted by ZeeOSix
Originally Posted by ZeeOSix
Originally Posted by Cujet
That chart makes little sense with regard to rod bearings. The clearances quoted have little resemblance to any previous or common era conventional engines.

I believe the Ford Coyote 5.0L V8 has minimum rod clearance of 0.001". I'll look in the factory sevice manual and snip-it and post later.


So I got around to looking up the main and rod clearances on the Ford Coyote 5.0L V8. As you can see they can be tight, around 0.001" minimum clearance. Even the piston to cylinder clearance can be pretty tight.

Even though the oil spec is 5W-20 for street use, Ford will recommend running 5W-50 for track use. So as usual, this shows that journal bearings (or other parts) clearance doesn't have much to do with what oil viscosity is specified for an engine.

 

[Mad_Hatter]

Originally Posted by ChrisD46
*I would also like to think - if say Hyundai/ Kia as example list owners manual approved oils as 5W20 , 5W30 and 10W30 (depending on ambient temps) then there is a bit of leeway in acceptable ouils based on key engine tolerances (albeit not as much as for the Mustang Coyote 5.0L).

That was the gist of a previous post of mine. There's no such thing as a perfect oil. It just doesn't exist. Perform in one area, say low oil friction is gonna come at the expense of viscosity (hths/MOFT).

The Kia engine builders know what grade(s) are going to provide that MOFT (5/20 in my case) to avoid catastrophic metal to metal contact and which oil is going to be too thick that flow (starvation) and friction (oil drag) becomes a potential issue. And I'm glad they're transparent in this and allowing me the owner some flexibility in lube choices without worrying that I'm gonna void a warranty. ...I said that Honda knows full well there are other lubes besides a 0w20 that will work just fine in their engine. Question is, why are they not transparent in this?...I mean seriously, what happens when that 0w20 thickens up to a Xw30..is that Honda engine gonna spontaneously grenade???...‚

 

[ZeeOSix]

Originally Posted by Mad_Hatter
The Kia engine builders know what grade(s) are going to provide that MOFT (5/20 in my case) to avoid catastrophic metal to metal contact and which oil is going to be too thick that flow (starvation) and friction (oil drag) becomes a potential issue.


I don't think there is any "oil starvation" unless a thick oil is used in temperatures much colder than what the oil is speced for. When car makers spec 0W-20 or 5W-20 then by default you get good cold weather cold start oil flow.

Using 10W-30 instead of 0W-20 in say above 50F weather isn't going to result in any oil starvation.

Originally Posted by Mad_Hatter
And I'm glad they're transparent in this and allowing me the owner some flexibility in lube choices without worrying that I'm gonna void a warranty. ...I said that Honda knows full well there are other lubes besides a 0w20 that will work just fine in their engine. Question is, why are they not transparent in this?...I mean seriously, what happens when that 0w20 thickens up to a Xw30..is that Honda engine gonna spontaneously grenade???...‚


Honda is playing the CAFE game pretty hard, therefore they won't even mention any oil viscosity options in their manuals. They might in countries outside the USA like other car makers do.

 

[Mad_Hatter]

Originally Posted by ZeeOSix
Originally Posted by Mad_Hatter
The Kia engine builders know what grade(s) are going to provide that MOFT (5/20 in my case) to avoid catastrophic metal to metal contact and which oil is going to be too thick that flow (starvation) and friction (oil drag) becomes a potential issue.


I don't think there is any "oil starvation" unless a thick oil is used in temperatures much colder than what the oil is speced for. When car makers spec 0W-20 or 5W-20 then by default you get good cold weather cold start oil flow.

Using 10W-30 instead of 0W-20 in say above 50F weather isn't going to result in any oil starvation.

Originally Posted by Mad_Hatter
And I'm glad they're transparent in this and allowing me the owner some flexibility in lube choices without worrying that I'm gonna void a warranty. ...I said that Honda knows full well there are other lubes besides a 0w20 that will work just fine in their engine. Question is, why are they not transparent in this?...I mean seriously, what happens when that 0w20 thickens up to a Xw30..is that Honda engine gonna spontaneously grenade???...‚


Honda is playing the CAFE game pretty hard, therefore they won't even mention any oil viscosity options in their manuals. They might in countries outside the USA like other car makers do.

In my original, in context, post I said a [gross] deviation of the recommended viscosities can cause oil starvation. Going from a 5w20 to a 10w30 generally wouldn't be considered a gross deviation...but going from a 5w20 to say a 15w40 might be. Just depends on factors like the engines pumping ability and tolerances. In older engines, thicker oil might be more desirable due to wider clearances in places like rings to piston. But...you go too thick and things like turbos and bearings can be starved of oil, or more accurately lack of lubrication. In these areas reduced flow and increased oil friction due to viscosity increase, can have potentially catastrophic effects.

The 2nd half i agree wholeheartedly...

 

[Lowflyer]

Originally Posted by Mad_Hatter

The Kia engine builders know what grade(s) are going to provide that MOFT (5/20 in my case) to avoid catastrophic metal to metal contact and which oil is going to be too thick that flow (starvation) and friction (oil drag) becomes a potential issue.
Of course. But this must not be a 5W-20.

WWOs (Wee-Wee Oils) are a result of fuel consumption hysteric, as result of climatic hysteric. You self, will never find those 2 things between 5W-20 and for example to M1 5W-30 (504/507):

1. for you measurable less fuel consumption (equal)
2. one molecule more wear in your UOAs (rather more)

In Kia engines not and in Subaru engines also not.

Without doubt, Kia engine builders know what grades are best. The problem is, they determine it not alone.

 

[dlundblad]

I can't see oil temps affecting coolant temps in any major way as the cooling system would just compensate for the higher temp within the engine. This is assuming the cooling system is 100% operational.

I believe oil temps would be higher with thicker oil, but I'm not sure that's a bad thing within reason.

 

[aquariuscsm]

Originally Posted by ZeeOSix
Honda is playing the CAFE game pretty hard, therefore they won't even mention any oil viscosity options in their manuals. They might in countries outside the USA like other car makers do.


This.

I saw an actual 2012 Accord owner's manual from another country and it says to use W30 oil.

 

[CarbonSteel]

Originally Posted by demarpaint
Originally Posted by ZeeOSix
Originally Posted by ZeeOSix
Originally Posted by Cujet
That chart makes little sense with regard to rod bearings. The clearances quoted have little resemblance to any previous or common era conventional engines.

I believe the Ford Coyote 5.0L V8 has minimum rod clearance of 0.001". I'll look in the factory sevice manual and snip-it and post later.


So I got around to looking up the main and rod clearances on the Ford Coyote 5.0L V8. As you can see they can be tight, around 0.001" minimum clearance. Even the piston to cylinder clearance can be pretty tight.

Even though the oil spec is 5W-20 for street use, Ford will recommend running 5W-50 for track use. So as usual, this shows that journal bearings (or other parts) clearance doesn't have much to do with what oil viscosity is specified for an engine.

So much for the engines are being built so tight they "must" have a 20 grade oil in order to operate properly and not self destruct, as some allude to here.