I debated whether to start the engine and let it warm up, then change the oil, or change the oil first before starting. Mine too has been sitting since October, 1986 560SL. I was changing to Mobil 1 from 5W30 Quaker State.
I decided that, since I'd run a couple of bottles of Risilone through it, late last summer, it would be better to drain and change the oil before starting....why distribute dirty oil all through the engine, and it has had all winter to drain down to the sump. I don't know if this was the right decision, but it seems logical to me.

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1986 560SL
2002 Toyota Camry
1993 Lexus