Originally Posted By: Lost1
Originally Posted By: Bulli
speaking of rod knock will heavier oil quiet down the knock?
5-30 is what is recommended. will 10-40 be ok?
10W-40 may work, but 20W-50 will probably work better.
Back when I used to keep vehicles long enough for the engine to start wearing out I would use a heavier oil to quiet rod knock. 20W-50 worked well & would usually add quite a few years & miles to the engine's life before overhaul was required. Adding a bottle or two of STP oil treatment to the 20W-50 would extend the life even further. I had a '79 Lincoln Mark V with a 400 that developed rod knock at 125,000 miles. Switched to 20W-50 with STP oil treatment in it and the engine was still running smooth, strong, and knock-free when I sold it in '89 with 165,000 miles on it.
This approach has been repeated numerous times over the years in my own vehicles, as well as those of friends and family members and has always worked great.
Give it a shot; if it already has a rod knocking you don't have much to lose, and plenty to gain...
You were not quieting a rod knock but rather a main bearing rattle. A rod bearing will go bad in no time.