You had oil on the electrode itself? Or on the threads?
The threads accumulate a small buildup over time from pcv usually, nothing really big.
If it was on the electrode itself then there was no way it was firing at all, as it would burn it off.
How is it running with the new plugs?
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BV heads, P&P lower, comp 218/226 cam, 4.2 bottom end, 3k stall, flow 40's, O/R x-pipe, Pacesetter lt's, SCT xcal2 (93 Ortizperformance tune), Windstar upper, 65mm tb, CAI, 8.8 w/ 3.73's, SFC's, cut springs, KYB shocks/struts, MM LCA's
blower/new cam soon
Dealer for Ortiz Performance, great tunes at a good price!