Engines that actually require Thick or Thin oil?

Status
Not open for further replies.
Originally Posted By: ZeeOSix
So the shop manual says the STD oil clearance range is:

Crank bearings: 0.0015~0.0029 inch.

Rod big end bearings: 0.0008~0.0020 inch.

And Toyota is specifying use of oil as thick as 20W-50 in a rod bearing that could be as tight as 0.0008 inch and still be within factory spec.


grin.gif
grin.gif
grin.gif
grin.gif
grin.gif
 
Originally Posted by PimTac
Originally Posted by Gokhan
Originally Posted by PimTac
�....Ha! You were being gaslighted all the time after all!....�

I have no idea what this means.

Ah, the phrase arises from the famous classic 1944 Ingrid Bergman movie Gaslight (based on a play written earlier), for which she won the best-actress Oscar. You should see it. It's a very good movie.




I�ll check it out.


For whatever reason, this thread reminded me of a story from my Dad who spoke of some unscrupulous used car dealers way back when that added sawdust to the oil to make the engine quiet. A poor man�s moly in that respect. This was in the 40�s as I recall.


What's with all the �s?
 
Originally Posted by Jackson_Slugger
What's with all the �s?


Probably posted from a cell phone, and the board doesn't like the apostrophe character.
 
Originally Posted by ZeeOSix
Originally Posted by Jackson_Slugger
What's with all the �s?


Probably posted from a cell phone, and the board doesn't like the apostrophe character.




So he resurrected a old thread just to ask that?
 
Originally Posted by PimTac
Originally Posted by ZeeOSix
Originally Posted by Jackson_Slugger
What's with all the �s?


Probably posted from a cell phone, and the board doesn't like the apostrophe character.




So he resurrected a old thread just to ask that?


This thread was linked to from a very recent thread, because it showed graphs of HTHS viscosity Vs Bearing wear, which came up in that thread.
 
Dr Hass turns over his cars frequently.
Originally Posted by rooflessVW
Supposedly the 5.7 Hemi "needs" a -20.

I prefer my oils to end with a -40 or -50.

Needs?
 
You could have an oil that has an insufficient MOFT (too thin) but you can't really have an oil that is too thick, correct? At least at operating temperature and within those oils readily obtainable. An oil can be too thick to pump at cold temperatures but how could an oil be so thick at operating temperature to cause damage?
 
Won't "too thick" just get hotter in a bearing and the heat will thin it out anyway ?

Other than that, parasitic loss etc … but that's not metal damage … just wasted fuel/money …

Only other thing that comes to mind is distribution (each flowpath in the lubrication system) or the impingement from an oil jet can vary with viscosity … "sling" … but all these things are likely very minor …
 
And of course a 5W20 at 10F is much thicker than a 10W30 at 200F, so if thickness was an issue, oil temperature would be the big problem. But it isn't an issue if you are within the cold starting design of the oil, where it can be effectively pumped. (0F for a 10Wx)
 
It's "one size fits all" for engines nowadays. Bearing clearances are very precise in all new engines, and overhead cam engines like lower "W" rated oil since oil needs to flow to the cams on top of the engine quicker in a cold start. 5w-30 has been the go-to for this. Now it's more like 5w-20 and 0w-20 in normal driving conditions. I'd bump it to 5w-30 if towing or driving up mountains all the time or something. 0w-30 and 0w-40 are in more expensive overhead cam engines with turbos.

Older pushrod engines without VVT or cylinder deactivation don't care much about thick oil unless it's freezing outside. There are less parts that oil needs to flow to. Go ahead and dump 10w-30 or thicker like 15w-40 in an engine like an LS1 as long as it's in summer. They may actually sound smoother if they are very high in miles. Pushrods can still benefit from 5w-30 or 0w-30 in winter.
 
"overhead cam engines like lower "W" rated oil since oil needs to flow to the cams on top of the engine quicker in a cold start."

There is no quicker, it either pumps or it doesn't. The same volume of oil per pump turn is moved, pushing oil down the galleys at the same rate, this morning at 52 f my Tacoma will not know the difference between a 0w20 and the 10w30 in the sump. The only way the oil will slow down is if the oil is at a temperature below its pumping viscosity.

Originally Posted by Loobit
It's "one size fits all" for engines nowadays. Bearing clearances are very precise in all new engines, and overhead cam engines like lower "W" rated oil since oil needs to flow to the cams on top of the engine quicker in a cold start. 5w-30 has been the go-to for this. Now it's more like 5w-20 and 0w-20 in normal driving conditions. I'd bump it to 5w-30 if towing or driving up mountains all the time or something. 0w-30 and 0w-40 are in more expensive overhead cam engines with turbos.

Older pushrod engines without VVT or cylinder deactivation don't care much about thick oil unless it's freezing outside. There are less parts that oil needs to flow to. Go ahead and dump 10w-30 or thicker like 15w-40 in an engine like an LS1 as long as it's in summer. They may actually sound smoother if they are very high in miles. Pushrods can still benefit from 5w-30 or 0w-30 in winter.
 
Status
Not open for further replies.
Back
Top