I know this is going against what others have said on this forum for years, but the rod bearing failures still don't go away. Rod bearing failure in these engines have nothing to do with the rod, bearing, or the quality of the build. It's not a clearance problem, out of round journal, finish of the journal, oil pump that keeps being changed without results. These engines have alot of oil in suspension. 24 oil squirters for the rockers, 10 cam journals, 12 piston oilers, mains, and the last in the chain to be oiled the rods, so their the first to starve for oil. If there were a problem with the build you would know it immediatly. I had 120,000 miles on my motor before it spun #3 rod bearing, so that wasn't caused by a build problem. The engine starved for oil. I have modified several FL3S members oil pans to add 1 1/2 qts of capacity to the stock oil pan. I have 20,000 miles on my build since rebuilding the engine without any problems. Going to a thicker oil makes the problem worse, it takes longer to return to the sump. I offered this service for $250 dollars, most thought it would be cheaper to take their chances. Some people have spun bearings on more than one engine, because they have'nt changed their approach to the problem. If you have a new bottom end with tight clearances,you shouldn't use an oil thicker than 10w30, even thinner would be better. Another thing that has been missed is that the oil is also used as a coolant to carry away the heat. If the oil is too thick, enough won't flow to keep the parts separated and cool. You will have high oil press, but it's not going where needed, just recirculating in the pump.
