[Cuda340]

This is an excellent video explaining oil viscosity and how lower viscosity oils can still protect your engine.

Will Thinner Oils Damage Your Engine? - YouTube

 

[LaChallenger2022]

I put this in my need to read/watch bookmark

 

[Rockster]

The piston does not stop at either end of its stroke. A trace of the piston's motion describes a sine wave. There is no flat spot at either the top or bottom of the wave.

Other than that...

His advice to use what the automaker recommends is good advice.

 

[A Guy]

Semantics...of course it stops, it has to to reverse direction, regardless of how the piston moves as it stops to reverse. Every piston stops at TDC and BDC...at 6,000RPM stopped is a relative term

A Guy

 

[ChallyTatum]

If you take the derivative of sinusoidal displacement (i.e. velocity) you will see the velocity of the piston is zero (stops) at the peaks and valleys of the sine wave.

 

[A Guy]

Note again that at TDC and again at BDC, the piston velocity is zero, because the piston reverses direction at those points, and in order to change direction, the piston must be stopped at some point.

Piston Motion: The Obvious and not-so-Obvious, by EPI, Inc.

A Guy

 

[ChallyTatum]

And then there are those who just don't get it.

 

[CE9311]

There is a feeling of comfort seeing an oil thread and knowing it won't turn into a whole salespitch. I love you guys.

 

[ChallyTatum]

There is a feeling of comfort seeing an oil thread and knowing it won't turn into a whole salespitch. I love you guys.

Oil always be there/here for you.

Sorry but I am trying to give up crude jokes.

 

[A Guy]

Lol, that was pretty slick

A Guy

 

[Rockster]

If you take the derivative of sinusoidal displacement (i.e. velocity) you will see the velocity of the piston is zero (stops) at the peaks and valleys of the sine wave.

Not according to what I was taught in geometry. For the velocity of the piston to become zero would require there be point on the crank journal that had a shape that allowed the piston to become stationary while the crank could continue to rotate.

Or another way of looking at this would be viewing the rod journal as the crank rotated there would have to be point the stopped moving.

 

[A Guy]

I'll just say this and then stop as I can't argue with physics. Any object that reverses direction has to stop to do so. Even if you throw a ball on an arc, at some point it has to go from ascending to descending and all velocity stops at that instant...period

A Guy

 

[ChallyTatum]

Not according to what I was taught in geometry. For the velocity of the piston to become zero would require there be point on the crank journal that had a shape that allowed the piston to become stationary while the crank could continue to rotate.

Or another way of looking at this would be viewing the rod journal as the crank rotated there would have to be point the stopped moving.

There is no other way to look at it.

 

[Rockster]

There is no other way to look at it.

Well, tell me you can see the piston stop in that video posted by A Guy.

 

[ChallyTatum]

Well, tell me you can see the piston stop in that video posted by A Guy.

I thought I just did? If the displacement of the piston can be described by a sine wave, taking the time derivative of that displacement will result in zero velocity (aka stopped) at the max (TDC) and min (BDC) displacement points.

http://www.idc-online.com/technical_references/pdfs/mechanical_engineering/Piston_Motion_Basics.pdf

 

[Bucko1]

Lets not get "crude". about it.

 

[ChallyTatum]

Lets not get "crude". about it.

On the contrary my response was refined.

 

[Bucko1]

No friction from me...

 

[Too Fast]

If the piston never stops, then how does it reverse direction, Rockster?

 

[CE9311]

On the contrary my response was refined.

Atleast it was also considered Top Tier!