Re: New Vehicle Oil Change?


"Joe" <really-faked-but-works@xxxxxxxx> wrote in message
news:Ou30k.41$pK.36@xxxxxxxxxxx
IMO, you should ignore all future advice from whoever told you to change
the oil in the first 50 miles because the source of their advice is
suspect.

Follow the maintenance schedule in your owner's manual for best and
cost-effective results. Changing the oil too early can interfere with
engine break-in.

I hear this all the time and as a machinist-of-sorts working with
tolerances at a higher level than Toyota, I wonder why or how this might
be true...

What would or could it interfere with? All I can think of is that maybe
the first batch of oil with the micro-residue from break-in sets the seals
in a certain way or maybe makes sure the rings are running on a surface in
a manner that "seats" them better.. To much proper lubrication can cause
too little break in when it is desired, but I would think an early oil
change would simply delay the break-in and remove possible large
contaminants that would possibly cause undesirable side effects.

Your thoughts are on the right track. Changing the oil early can delay
break-in and prevent proper piston ring-to-bore fit.

Since you are familiar with machining, you know that modern machine tools
can achieve a cylinder bore finish that used to be possible only by grinding
with a jig borer - almost mirror-like, yet automakers purposely leave a fine
cross-hatch finish on the cylinder walls. The ridges on the cross-hatch and
very fine particles suspended in the motor oil help the piston rings seat
properly, and after the cross-hatch has worn off, piston ring seating slows
down greatly. If the rings do not seat properly, you get more blow-by,
reduced power, and greater oil consumption

Conventional wisdom used to call for a very early oil change to remove metal
particles large enough to damage the engine, but modern oil filters trap
that stuff so very early oil changes are no longer necessary or even
desireble.

--

Ray O
(correct punctuation to reply)


.

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