Toyota Repair: 2005 Sienna Engine Flush, oil pressure loss, crankshaft seal

Question
Opened oil cap on top of engine and noticed hard residue covering almost entire opening. Have to admit I have not change oil as frequently as I should. Friend suggested engine flush but I was thinking of removing cover and cleaning before forcing all this stuff through the engine. Is this a good idea? Is there anything else that should also be done? Was warned that if oil screen clogs severe damage will follow. How do I check it? If there are other covers to be removed, what torque should they be reinstalled to? Are there any seals or gaskets I have to replace as well? Know its a lot, but thanks.

Answer
I would go ahead and try the engine flaush which should dissolve most of the oil gel undles it's really bad, I would remove the valve cover and inspect the valves and cams, flushing the engine may not remove a bad build up of sludge/oil gel. Yes, if the oil pump pickup screen gets blocked enough it can cause engine damage due to oil pressure loss. There are seals on the front of the engine, camshaft seals, crankshaft seal, the engine main seal is at the rear of the engine and to replace it the transmission has to be removed, so it depends if these seals are leaking. So I would first remove the front valve cover and inspect to see just how bad it is, if not too bad then the engine flushing will help some.