Re: Oil Viscosity for DOHC Ford
BTW - to meet SM-GF4 spec all oils a few years ago became semi synthetic even if it doesn't say so on the bottle.
A modern full synthetic only gives you about 30F more heat capacity before it breaks down over a modern "dino" oil. That gap was closed dramatically in the last 15 years. Many times its speced on the performance cars just so the manufacturer doesn't have to install an oil cooler for all units to account for the few that actually will autoX or road race them (true in the case of the Corvette)
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