Clearly, the engineering staff at PCM/Crusader was remiss in not consulting you prior to publishing their
conclusions. I feel that you would be doing the boating public a service by contacting these engineers
and letting them know how stupid they are.

Gene Kearns wrote:

On Fri, 19 Dec 2003 04:35:22 GMT, Jim Kelly wrote:

Gene,
Hydrodynamic lubrication takes place regardless of the type of oil used.

Only in a perfect world. If such were the case there never would be
any engine wear.

In the case of a plain
bearing such as those used on the crankshaft, there are conditions when boundary layer lubrication is
present such as upon start up. After the crank picks up speed, a wedge shaped film of oil is present
that is created by the hydrodynamic forces. At this point, their is full film lubrication.

This doesn't explain other parts of the engine subject to extreme
pressures, like cam-tappet wear surfaces. Everybody seems to think in
terms of "cold pumpability," but the fact of the matters is a lot of
engine parts are lubricated via splash. Molasses thick cold oil
doesn't splash very well (and too-hot oil will stick rings in a
jiffy).

The
additives you mention do not change this. If their never existed a boundary layer condition, there
would never be any bearing or journal wear and the bearings would last indefinitely. Whether you use
conventional or synthetic, this is not the case.

True, but the additives I mentioned will prevent galling and help the
wear parts over that inevitable metal-metal touch. You seem, now, to
me making my point. Why would getting the oil pumped to operating
pressure faster not force a quicker move from boundary to hydrodynamic
lubrication? Wouldn't that help prevent boundary lubrication problems?
You seem to be on both sides of the synthetic/dino fence, now!

Crusader Marine Engines did a study on this a few
years ago and came to the conclusion that, under normal operating conditions, there was no benefit to
using synthetics in their engines.


Yeah, there verbiage is:

"Synthetic engine oils are not recommended for use
in Crusader Engines. Synthetics may offer advantages
in cold temperature pumpability and high temperature
oxidation-resistance. However, synthetic oils have not
proven to provide operational or economic benefits over
conventional petroleum-based oils in Crusader Engines.
Their use does not permit the extension of oil change
intervals."

My issue with them is, "in a perfect world - not too hot, not too cold
synthetics just aren't necessary in our engines." Well, duh! I plan
for Murphy's Law, not Pollyanna's law of engine dynamics.... and at
the acquisition and repair costs of these engines, everyone would be
well advised to do likewise..

Oil is a helluva lot cheaper than repair and replacement.

--

Grady-White Gulfstream, out of Southport, NC.

http://myworkshop.idleplay.net/cavern/ Homepage
http://www.southharbourvillage.com/directions.asp Where Southport,NC is located.
http://www.southharbourvillage.com/autoupdater.htm Real Time Pictures at My Marina
http://www.thebayguide.com/rec.boats Rec.boats at Lee Yeaton's Bayguide