yes oil can be bad for a starter and solenoid. Try this. Turn the key to the on position (dont try and start it) block the tires so it cant roll and be sure that its in park. At the starter solenoid there are 3 wires. 2 Large gage wires and one smaller one. Expose the smaller wire so that you can see the post (meaning make it so you can see the metal post) Take a screw driver (or other metal object that has an insulated handle) and cross the small wire to the larger wire coming from the battery. It should turn over. If it does then the problem is in the wiring from the switch.
1998 ZJ 5.2 Auto
1989 Wrangler Black Bone Stock 2.5l 5spd
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