On Tue, 27 Mar 2007 18:07:37 GMT, "Speeders & Drunk Drivers are
"Engines last forever if you change the oil frequently".
Where did you come up with THAT?
For all you frequent oil change advocates, keep in mind that MOST
engine wear occurs after cold starts, when the bearings and other
surfaces are relatively dry of oil.
You can change the oil at 100 miles intervals and you won't reduce the
wear from cold starts.
Lots of testing has been done over many years which proves that.
About 25 years back, Popular Mechanics mag did a review of a gizmo
system that prelubed cold engines by pressurizing the oil gallerys via
an electric pump and a timer that delayed ignition during starts until
all oil passages were pressurized. However, it was fairly complex and
most owners wouldn't want to be bothered.
Some heavy truck engine makers have tried the same thing and so do
some maritime engines.
One reason why taxi and other fleet engine use achieved high mileage
before engine teardowns is simply the fact that the engines are
started once a day and never shut off during the hours of use.
BTW, in maritime HEAVY diesel applications, under conditions far more
severe than auto useage, oil is NEVER changed.
I've served about ships with huge 4 story high 38,000 HP slow speed
diesel engines. Lube oil is distributed by separate pumps from a huge
reserve. The reserve is replenished as it drops by pumping in new oil.
The oil is purified after it passes thru the engine by being slung at
high speed in centrifugal oil purifiers where all solid matter is spun
out. At 30 day intervals, samples of lube oil are sent to a laboratory
for analysis. the amount of bearing material suspended in the oil is
noted to determine wear rate of the engine. The lab recommends
additives as necessary and the oil is continuously used.
The bearing loads in these engines are astronomical compared with auto
engines. There's nothing like seeing a 5 ft diameter piston going up
and down in a 15 ft stroke,with an output power of 5,000 HP per
cylinder... The internal cylinder pressures are extremely high since
these engines are also turbocharged. There nothing like those turbos
screaming away in the engine room. Their sound level is up around 135
db's. Ear muffs are neccesary or you go deaf in minutes.
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