Sounds like you got a good all around winter oil in there. I ran 20w/50 all year round over hear, but my climate is mild to say the least. Up your way this time of year, that 10w/30 is sounding pretty good, if it wasn't for the fact that we're trying to eliminate (or at least reduce) a potential bearing knock.
Maybe leave it for awhile and just add some of the snake-oil to that synthetic you have in there now?
At the very least, that way you'll waste one less batch of oil, and at the best, you're running a good winter blend it sounds to me.
Wait for others to chime in, that might have more experience in the Eastern Winters than this left coast yankee. Lots of VA Bronco owners that can talk about oil weights and oil pressures and such in your region.
My own experience sounds similar to yours to an extent. When mine had only 60k miles on it, there were already clicking noises from the lifters, it smoked out the tail pipe and used a quart of oil every 500 miles or so. And it just didn't have a whole lot of giddy-up for a 302 either.
In fact, the day I picked it up we checked the dipstick while still in the PO's driveway, and found that it had only 1 quart of oil left in it!!!!
Funny thing about oil pressure in an engine like ours. Because it was only running at low rpm, that one quart was actually enough to keep from sucking air (barely) because there was probably some still up in the filter and galleries and such (so more like 1-2 quarts?) but it took over two quarts just to start registering on the dipstick!
Luckily he had a case of oil in the garage.
Sorry for the long story. But basically, after a few oil changes, a few cans of oil cleaning additives (as opposed to the thicker STP stuff I was suggesting for yours) and a month or two of daily driving duties, all the smoking went away, the ticking lifters went away, the miles-per-quart went up to near 5000(!) and all was well with the engine for another 110k miles or so that I put on it. Sold it with 175k on the clock, still running like a top for someone to use while they rebuilt their old engine.
So it can work...
One thing I started to say previously, but sidetracked my train of thought, was that due to your possible high sludge content, you really don't want to use any of the solvent-based additives, such as the ones I used on mine, that are just meant to clean things up. Without a good manual cleaning first, you could dislodge larger volumes of sludge from inside and gum up the works.
I would still use the STP or Motor Honey types. Just not the thin cleaners yet.
Actually, I personally would still use them to clean up an engine in my own vehicles, but from experience would hesitate to recommend it to others unless they're ready for the possible consequences. In those cases, I'd open up the other valve cover to see what condition the upper areas are in before solvents get added. If it's bad, better to manually clean some of the stuff out first.
If it's not too bad, then have at it.
If your initial inspection didn't really indicate a huge amount of sludge (you didn't say how much, just that it had some), then there should be no reason to worry. I just like to bring it up because of the possible results under varied conditions.
With your knock however, we're still talking about the thicker additives just to see if it helps pressure and quieting the knock.
Be interested to hear what your pressure gauge is reading at the moment.
Good luck. Enjoy the driving around getting used to your new/old ride.
Paul
