FrancisFarris wrote:
As long as an old sludged up engine is running fine without any issues, what’s there to unmask? God forbid but if there is to be a catastrophic failure by using non detergent oil, it certainly will occur sooner using HD oil in an old original engine. I change my oil once a year every summer and I typically drive the car about 300 miles a year. I use 40W non-detergent. Every time I remove the oil strainer screen, I am amazed how dirt and scum free it is.
I'm not arguing with whatever you want to do to your car. I'm only speaking to the mechanics (engineering view) of sludge in an engine. In a worn bearing, sludge at the exit of the oil flow will act as a dam to reduce flow out of the bearing, keeping it it lubricated. It also plugs oil passages and prevents oil from flowing to other areas in the volume that was intended. This "masks" what is happening mechanically in a worn, sludged engine, keeping it operating until bearing get so bad that the y wear out, score journals, etc. You won't see sludged oil at your oil change given the frequency of your oil changes. It builds up in the engine and clings to the internal surfaces. Using detergent oil keeps these surfaces clean, sludge free. The ONLY way detergent oil leads to a quicker catastrophic failure is if you switch, and DO NOT inspect and correct problems like worn bearings, journals etc. That's why I specified, inspection and repair. I have no problem on you doing what you want with your car. But given the lack of readily available replacements parts for our cars, I choose to inspect and repair my engines and run with a KNOWN good engine while using detergent oil to keep the internals clean rather than running an old "unknown conition" engine because it still sounds good.