On Mon, 21 May 2007 03:21:06 +0000, Larry wrote:

The numbers look different at 15,000 hours

That's *not* going to happen with a 3600 RPM air cooled diesel. I'll
be surprised if it makes 1500 hours at half load, even if you change
the oil every day.

On May 21, 11:40 am, Wayne.B wrote:

That's *not* going to happen with a 3600 RPM air cooled diesel. I'll be surprised if it makes 1500 hours at half load, even if you change the oil every day.

I thought contemporary wisdom was that frequent, such as daily, oil
changes were a BAD thing with modern lubricating oils?

Modern oils with zinc and phosphorus additives require a certain
minimum amount of operating engine time to reach the lability point of
the organometal additives. The chelated zinc and phosophorus additives
are designed to be labile, so the ligand molecule will surrender its
metal load into a micro-void on the surface of a stressed engine part
(eg a bearing surface) when the ligand molecule has been stressed by a
heat/pressure event. The surrendered zinc, phosphorus or whatever
additive, by its deformation (because it's softer than the steel
bearing surface), is what protects the bearing surface.

Changing the oil too frequently prevents the additives doing what they
were designed to do. Of course, changing the oil frequently boosts oil
corporation profits. And if you're holding stock in Big Oil, that's
not a bad thing either.

Bil wrote in news:1179801332.742087.12070
@x35g2000prf.googlegroups.com:

Changing the oil too frequently prevents the additives doing what they
were designed to do. Of course, changing the oil frequently boosts oil
corporation profits. And if you're holding stock in Big Oil, that's
not a bad thing either.



What you say is true of a gasoline engine. But, in any diesel situation,
the big oil destroyer is carbon from all the blowby of the insanely
pressurized combustion caused by the 22:1 compression ratio and that
knocking explosion blowing it by even good rings.

The oil turns to carbon in a short time. Just pull the dipstick after an
hour of runtime and wipe it on your best shirt. It'll remind you to
change it OFTEN....not wait for amazing modern additives, now embedded in
lamp black, to coat the bearings. They can't even SEE the bearings!...
(c;

Larry
--
Grade School Physics Factoid:
A building cannot freefall into its own footprint without
skilled demolition.