if the car is not running when you unscrew the oil line.. you shouldnt get much more than maybe a drip.... while your cluster is out in the open.. might as well get some rug and clean the bulbs (if you havent cleaned them yet).. as they get dirty through time. Remove the speedo cluster, the oil/fuel/temp cluster and the clock/tach-clock and clean the clusters... if you want you could paint the needles if they have lost their luminiscense (spell check here..
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i think what dieseldiehard is implying is dont forget to screw back the oil line firmly.. otherwise when you start your car.. you'd get squirts of oil coming from the back of the dash.... and its a messy job cleaning it.