Mike, a piece of sludge could have been hanging out in the gallery for a long
time. Once you switched to Mobil 1, you were probably driving the car harder,
and the 15w50 viscosity made the oil run hotter (generally, a good thing, since
high oil temperature ironically resists sludge formation). This combined to
your very bad luck could have moved the sludge to partly block an oil passage.
Then, the oil pressure reading dropped, since the sensor is at the back of the
cam. Also, one or two cam bearings saw very low oil flow, ran too hot, and
most important, ran dry longer at startup. This high cam friction (especially
during startup) fatigued the cam. The super high quality oil probably helped
to postpone the final failure.
Its hard to tell for sure, but that's a good theory. Yes, in retrospect you
should have installed the mechanical oil pressure gauge. Its easy to say that
now of course!
D^2
Quoting Mike Pittinaro <mechimike@xxxxxxxxx>:
> As far as sludge goes...I would think it would have
> reared its ugly head long before now. >
> Interestingly, almost immediately after I switched to
> the Mobil 1, I noticed a drop in the oil pressure
> gauge; normally it rode about in the middle of the
> range, and after the switch it went to about 1/4 to
> 1/3 of the range. I figured maybe the gauge was bad,
> or maybe the different oil made the sensor read
> differently. Stupid me, I never installed an
> aftermarket gauge.
>
Back to the Home of the Forward Look Network