If the oil pressure takes some time to go to maximum after you've started the engine after it has been stopped for a while then it is likely that the oil filter return valve is duff. Oil could be draining out of the filter into the sump - it then takes a bit of time to get the filter filled when you start the engine again and the top end of the engine rattles because it is being starved of oil...

...if it is this - solution is to put on a good quality oil filter.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!