Obvious but you'd be surprised how many people make this mistake...
Be sure you have enough oil in the engine...
You may be right about the clogged system from the nasty oil
Run up to murrays and buy an oil pan gasket and some oil system flush. Run the flush through your engine (the 5 minute stuff by Eagle) and drain your oil. Then drop the oil pan and clean out all the sludge and debris that's now resting on the bottom of your oil pan.
You'll be surprised by what will come out.Total cost is something like 12 bucks