Troubled Volvo B23a Engine (Loud noise and knocks when cold starting)

Hi, everyone !

Glad to join You all right here, this will be my ever first thread to share with You !
We have a 244DL with B23A under the hood and correct me if I am wrong but I’ve read that this particular one has a distinctive thing over the B19/B21 engines aside from the capacity which is the Two water Plugs on both sides of the block, to make it clear and in brief We used to have 20W50 oil lubing it instead of the standard 10W30 all for being overpriced (not here to bring my drama) and was left in for a year and couple of weeks that when changed it seemed to lose its characteristics and it’d shear (certainly it Would after this long), back to the basic issue whenever this engine is cold started, I can hear some violent knocks noise that doesn’t last for minute but later on it got worse and it actually lasted way longer than It used to that It takes a long while about over (5 minutes) and still to get quieter, it worths mentioning that I can also hear some rattling sound afterwards when idling at about 750-800 RPM.
started to get skeptical about the oil pump, Crankshaft main bearings, Camshaft Bearings.

Any ideas or pieces of advice on this one and I’ll be Grateful, Thanks

Time to get it to a shop and get the oil pressure tested with a mechanical gauge.
I believe the B23’s runs on 15W40 oil. If that is correct, neither the 10W30 nor the 20W50 did it any good.

Different car, but sounded like valve clatter etc. when starting, it ended up being a bad tensioner. Leave it overnight at a mechanic?

Mechanical lifters and they are not known for cam wear on the B23. A few cams on the B17, B19 and B21’s wore the lobes off, but it was rare.

doesn’t seem to be a timing belt/ tesioner issue, the sound seems to come from within the engine.