I use 20W-50 because that is the MB recommended oil for the 117 engines for climates that get up to 100 deg F, which it does here in the summer and very rarely gets down to 32 deg. In a SBC I would never run 20-50. On a SBC 5 psi is safe at idle if the engine is stock. Don't know about a MB engine. Anyone know what the safe minimum oil pressure is for MB engines?

Paul

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84 500 SEL (307,xxx miles)