I understand that......but some were saying the 15W/50 was like 50W when cold and it is NOT. Would you think straight 15W was too thick given his combo?......No and neither would anyone else and that is the SAE standard that 15W/50 oil MUST meet when cold. My point was that is wasn't the oil that caused the problem.
He said he had .002. Well how was that checked? With plasti-gauge or with mics. And if mics were used, was it only checked 90* from the parting line in a torqued rod, or in several places. The rod could have been out of round, or the crank pin had taper or wasn't round. .002 in one spot, doesn't mean it had .002 everywhere. I still think it was just tight for some reason. If you want to run em tight, that's fine, but it better be right everywhere
You dont pick an oil based on the winter grade number unless you are running in sub freezing temps.
Viscosity is based on oil temp.
His oil acted like a 50 grade oil when at operating temp.
That seems heavy for his clearance.
I don't use Gibbs so I can't say why they picked a 50 grade oil. I would have used a quality 30 grade.
The oil timing is off on these engines. At the speed the OP is turning he needs a full groove bearing to get oil to the rods on time, or close to it.
The only fixes for high RPM (over 8k) are have a crank drilled to the correct oil timing, but I have never had it done.
Or, you have to bring the oil to the crank in a different place to correct the timing.
And that is a whole nother thread.
