On Sat, 17 Dec 2005 22:10:13 GMT, Gene Kearns
wrote:


When changing oil, you don't have a dry start... unless you have
figured out a way to suck the oil from between the bearing/journal
clearances.

You are correct, however,"dry start" is a term used in the engine
industry for when an engine is turning over or running with "less than
spec" oil pressure.

I've pulled apart engines that have sat for *years* and
there was still a film of oil coating the journals and bearings. Recip
aircraft engines are run up to 30 seconds with NO oil pressure showing
on the gage....with no damage expected... per the manufacturers
manual.

"Expected" damage is subjective.

Oil will lubricate with NO pressure... and does, every time
you start your engine.

Lubricate, yes. Gene, do you know the dynamics of a pressurized galley
and Babbitt bearing system?

If the quality of your oil does not provide for boundary lubrication
as well as hydrodynamic... you've got problems, anyway.

Um...agreed.

Pre-oiling is preferred, but running dirty oil is just recycling what
amounts to abrasives through the engine.

Um...agreed again.

Our lab did extensive testing on the subject, and found that (of
course) engine with more dry run time had *significantly* more
wear/damage.

Citation?

I don't have any of the documentation from that study, but I read the
results, and saw/measured the damage myself.

How many percent do you have to turn on that turbine engine before you
have any oil pressure?

Less than 1%.

But then turbines run forever between oil
changes, don't they!

No.

Wonder why?

No. I know why.

You do have your supporters, though... Jaxashby ranted on for months
in support of your position...

Its not a position of support...its fact.

Take care Gene.

__

"It's just about going fast...that's all..."

http://home.columbus.rr.com/ckg/