Varnish dynamics in big machines

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Originally Posted By: Trav
So much for varnish is just a "cosmetic" stain we read so many times.
Thanks!A very interesting read.


+1
 
Originally Posted By: Trav
So much for varnish is just a "cosmetic" stain we read so many times.
Thanks!A very interesting read.
There is a whole lot of difference in a turbine and a gasoline engine.
 
There's a heap of difference.

It's got me wondering 'though how much sludge in engines is created by micro dieseling in aerated oil as people run their sumps lower and lower.
 
Just heard today that Caltex are changing their turbine oils to GrII, from Gr I.

That's going to make the state interesting for a while
 
Originally Posted By: Steve S
Originally Posted By: Trav
So much for varnish is just a "cosmetic" stain we read so many times.
Thanks!A very interesting read.
There is a whole lot of difference in a turbine and a gasoline engine.


I don't disagree but even in gasoline engines there are components that suffer from sticking or reduced performance because of varnish i.e piston rings,hydraulic lifter/lash adjuster.timing chain tensioners,VVT systems etc.

I still maintain that varnish is much worse an issue than some would have us believe.
I also wonder if if the coating of varnish doesn't provide a good foundation for sludge to form upon.
 
Yeah that is the reason you change the oil in a timly manor as not to deplete the adds that keep the crud down to an acceptable level.
 
Originally Posted By: Shannow
There's a heap of difference.

It's got me wondering 'though how much sludge in engines is created by micro dieseling in aerated oil as people run their sumps lower and lower.
Running the sump down? it is safe to operate the engine with the oil any where between the add and full lines . But with running the oil way to long the antifoam adds deplete and that may be something to ponder? Will the pressure in a gasoline engine be high enough to cause the micro dieseling? Or when the bubble collapses could that start the micro dieseling . Then would the temp the oil ignites have something to do with the dieseling? Could that be why some UOAS have high nitration and oxidation levels? Better not to even think about it .
 
Doing some number crunching.

Adiabatic compression of a bubble across an automotive oil pump could give 175C temps.

So concievably, on the lead in side of a bearing, leading up to establishment of the wedge pressure, temps could be very much higher.
 
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