I found that out the hard way. When I went to rebuild the engine I am putting in my truck now, I found chunks of plastic guide stuck to the oil pickup tube. Long story short, PO had a shop change out the timing chain, shop did not take pieces out of oil pan, pieces get sucked onto pickup tube, engine loses oil pressure, timing chain skips, valves are destroyed and the engine runs like
Here is a pic of the pieces i found sucked onto the pickup tube with a dorito for size comparison:
