as for oil pressure isnt it something like 3 psi per 100 rpm rule of thumb on diesels?

as for draining the cooler, imo, theres no plug. odds are the car is 25+ years old, it hasnt been done in 25 years, why start now?

if u add a drain its just more stuff to leak, i dont like having extra parts that could potentially break.

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95 E320 24k
07 E550 4matic 20k Soon to go
1977 240d 481k
2013 SL 600


Non MBs

02 Ford F250 Lariat 4 Quad Cab 7.3 Diesel 95k
01 Chevy Suburban 249K LT 5.3 V8
88 Saab SPG Convertible 32k
06 Lincoln Mark LT 59k
62 VW Bug
52 Bentley Mark IV
53 GMC half Ton Pickup
08 VW Beetle convertible 2k
07 bmw x5 4.8i 17k
03 bmw x5 4.4i 40k
08 Range Rover S 9K