These engines absolutely, positively must have their oil meticulously maintained at the "full" line.
The rate of oil return from the cylinder heads appears to be a problem which can lead to an emptying of the oil pan into the valve covers in short order at high RPM, leading to oil starvation at the pickup tube if the level was too low to start with.
If there was no oil on the stick, you've just taken it to 6K and now have a knock, I'd say the motor has probably spun a bearing.
I check my oil every fill up.
The rate of oil return from the cylinder heads appears to be a problem which can lead to an emptying of the oil pan into the valve covers in short order at high RPM, leading to oil starvation at the pickup tube if the level was too low to start with.
If there was no oil on the stick, you've just taken it to 6K and now have a knock, I'd say the motor has probably spun a bearing.
I check my oil every fill up.