For spun bearings, yes. I have seen some that become more prominent with the engine heated, depending on what the connecting rod is made of. The big end wraps around the crank, and typically the crank is a much more resistant metal. Depending on how the bearing is worn, it can oblong the bearing. When the engine is cold the metal can contract and cause a tighter fit around the crank. When its heated, the connecting rod expands a little larger then the crank itself and cause a smidgen of a gap (like 1000ths of an inch), and its usually cushioned by oil coming through a journal in the crank so there is no noise. But if the gap is too large, you will hear it smack into the connecting rod on the power stroke, and sometimes when another piston hits its power stroke as the crank is suddenly pulled away from the crank. The bearing isnt really a bearing like you would think in the sense of a wheel bearing, but its more of a race that rides around a smoothed portion of the crank.
But what I keep scratching my head over is the way this one works.. In that specific RPM range. I've seen a lot of 5.7l vortecs with spun bearings and usually right from start up and through the range, you will hear the knock.
I don't know if running synthetic would help at all. I suppose really all we can do at this point is wait until the wear increases and we have something more concrete to work with. It's not like I can do with my old chev and dodge and just pull the oil pan and check the bottom of each rod for play. Not so simple when dealing with warranty covered bits..
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View my fuel log 2015 Micra S automatic: 7.9 L/100 km ... 35.7 mpg (Imp) ... 12.6 km/L ... 29.7 mpg (US) ...