I'll chime in here and relate what I experienced. I was using a lot of oil, blow by etc. I agree with the push it hard recommendation. Give Marvel a try. My blow by is much less and oil consumption is down considerably. My compression now is roughly 5-10 psi higher across all cylinders now. I copied and pasted below my response to member Camp back on Sept 5th 2024. Marvel is around here at Walmart, about $7-8.00 a quart. I did the full 20% as listed on the bottle for each oil change. I now routinely add 1 quart of Marvel Oil at regular oil changes, and put a half bottle in the fuel tank at fill ups every second or third fill up.
Not saying it's a cure all, but do give the mystery oil a try. When I bought my truck a NA 7.3, it had sat a while. Compression averaged out at 405 lbs, 375 low 440 high. But there was considerable blow by. I noticed it would actually push my dipstick up out of the tube, a weeping rear main seal, and this was after I had already changed out the CDR. Engine ran just fine otherwise, couple, three quarts of oil every 300-500 miles. Now, using Chevron Delo 15W-40 plus quart of Marvel, with a new filter each time, I changed oil, filter, and Marvel at about 750-1000 mi interval three times to sort of flush the engine out, and now blow by is very minimal, weeping rear main nearly cleared up, dipstick stays put. If the rings were stuck before, they must have been freed up some now. Would be interesting to check the compression now to see where each cylinder stands.
I'd have to give Marvel Mystery Oil a thumbs up. I also favor Chevron Delo syn blend now. around here in Florida, at Walmart, it's cheaper than the other diesel oils.