Are thinner oils about fuel economy or tighter engines?

[MolaKule]

@ZeeOSix
@ArthurArgentum

Suggestion: Do your calcs for both the mid-stream flow rate in m/s and Volumetric Flow rate in m3/s or Mass Flow Rate in kg/s for two kinematic viscosities--7.0cSt and 19cSt. You can also assume rho ρ = 891 kg/m3 or use your own oil density figures.

Assume an initial pool of oil contained in a volume of 5,202mm3, or 51mm in Height and 102mm square. (Visualize a funnel with a square top and circular tube, if you will).

Assume Laminar flow (Re
The length of the oil hole tube (drain back orifice tube) is 458mm.

 

[ZeeOSix]

@ZeeOSix
@ArthurArgentum

Suggestion: Do your calcs for both the mid-stream flow rate in m/s and Volumetric Flow rate in kg/m3 for two kinematic viscosities--7.0cSt and 19cSt. You can also assume rho ρ = 891 kg/m3 or use your own oil density figures.

Assume an initial pool of oil contained in a volume of 5,202mm3, or 51mm in Height and 102mm square. (Visualize a funnel with a square top and circular tube, if you will).

Assume Laminar flow (Re
The length of the oil hole tube (drain back orifice tube) is 458mm.

Depending on the engine design, there could be many drain back paths to the oil pan, and all their flow area combined (with parallel paths) would be pretty huge. If you had a funnel with a 1.5-inch diameter hole that was pretty short (essentially an orifice), anyone would know that any oil viscosity between xW-8 and xW-60 at 100C is going to scream through a hole of that size under the force of gravity that big and short. Like the Subaru example, imagine an engine PD oil pump screaming at 15 GPM and how much of that oil has to drain back to the sump from all points of the oiling system. Of course all the oil that flows out the sides of the crankshaft and rod bearings just falls directly into the sump. Only the oil volume pumped to the top end of the engine needs to "fall back by gravity" to the sump through drain paths.

 

[MolaKule]

Depending on the engine design, there could be many drain back paths to the oil pan, and all their flow area combined (with parallel paths) would be pretty huge. If you had a funnel with a 1.5-inch diameter hole that was pretty short (essentially an orifice), anyone would know that any oil viscosity between xW-8 and xW-60 at 100C is going to scream through a hole of that size under the force of gravity that big and short. Like the Subaru example, imagine an engine PD oil pump screaming at 15 GPM and how much of that oil has to drain back to the sump from all points of the oiling system. Of course all the oil that flows out the sides of the crankshaft and rod bearings just falls directly into the sump. Only the oil volume pumped to the top end of the engine needs to "fall back by gravity" to the sump through drain paths.

Well, you could do the flow calculations to prove your claims by using the simple proposed example above.

The inner diameter for the tube in the proposed example is 1/2" or 12.5 mm and is vertical.

This is a simple flow-by-gravity experiment to determine flow rates.

 

[midobo]

You guys are being trolled by someone using ChatGPT

 

[ZeeOSix]

You guys are being trolled by someone using ChatGPT

Guess it too has human like misconceptions, lol.

 

[Nesterenko]

When discussing the use of thinner or thicker oil, it is essential to consider the perspective of an average, which are based on average conditions. These considerations encompass the prevailing average formulations of thinner and thicker PCMOs available in the market.

Speaking of pretty words." Encompass the prevailing average formulations"? Okay then.

 

[ArthurArgentum]

@MolaKule
@ZeeOSix

I think determining the exact quantity of oil that flows out from the head is quite a challenging task, but it is not entirely impossible. But calculating the precise amount of oil that flows downward in the engine block poses its own unique set of difficulties. The presence of oil jets some contributes to the overall oil flow, and there are instances where oil can make its way down without defined channels or orifices. Additionally, we must consider the formation of mist, its subsequent aggregation, and the eventual runoff, especially in narrow areas.

 

[dnewton3]

What Mola is trying to do is get you to prove your point is plausible and potentially viable, or it's not. Forget the tangential issues; stick to the given parameters. As long as you apply the same assumptions to both vis conditions, there is balance in approach. Do the math and show your work, so to speak.

Otherwise, pipe down and walk away.