Dumb Oil Question

["Warren, Howard" <HKWARREN@xxxxxxxxxxxx>]

Okay, maybe this is a dumb question, but I'm going to ask it anyway <g>.

When I bought my Milano last December, I had my Alfa dealer change the
timing belt, front donut, a couple of hoses, etc., because the car had
sat undriven for almost a year.  He threw in a free oil and filter
change.  This same dealer had been the previous owner's mechanic, too.
He had used Pennzoil 20-50 in this Milano for its entire 140k mile life.

Now since I've owned it, without realizing the previous owner had used
Pennzoil, I've been using Castrol 20-50.  Since selling my Spider this
past summer, I've been driving the Milano a lot more on the highway, and
I've noticed my oil consumption has increased to about 1 qt/500 miles.
I've gone through three oil changes with Castrol.

Dumb question time: could my changing brands have contributed to the
increase in oil consumption?  Or is it just that I'm driving longer
distance trips?

Howard K. Warren, Little Rock, AR
1988 Milano Platinum, "Snow Hawk", 152k miles 

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