Castrol or Pennzoil?

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Oct 11, 2002
Pullman WA
I've been using castrol GTX for a while now, but based upon some of the used oil test results I've seen here I've noticed that Castrol seems to loose it's viscosity faster than Pennzoil, they both have similar amounts of moly content so who thinks that Pennzoil is the better OTC oil?? I'm considering making the switch in a couple of my older cars.
I ran Penn 10w-30 in everything I've owned for 30 years. Ran Mobil 1 for a few years on extended drain. I now run Schaeffer's 15w-40 in all my vehicles on an extended drain routine. The Schaeffer's saves me around $1.25/qt and last just as long as the Mobil 1.

On a 3000 mile change routine any decent oil will live that long in most engines. If you have any doubts do an analysis.

I would not push any common oil past the OEM guidelines without analysis.
I have a preference for Pennzoil also because it has such nice specs. I haven't seen any back-to-back oil analysis comparisons between the two oils though.

[ March 06, 2003, 04:16 PM: Message edited by: Jay ]
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