I've had this car about 5 months. From the first day, it had about 70lbs oil pressure when cold, which gradually dropped to about 40 at highway speeds. At idle, once warm. the pressure drops to about 10lbs. 2000rpm at idle brings her up to about 25lbs. A few days ago, she developed a light knock starting at about 40 to 50mph, taching a little over 2000. This noise happens under steady cruise with a light load. Under hard acceleration or rapid deceleration, the noise goes away. For the past two days, the noise level has increased. It's a distinct loud rap. My fan has no clutch so the fan noise is making it hard to hear, but it sounds like it's coming from the front of the engine but my hearing ain't what she used to be, so I'm not sure. I run Mobil 10-30 along with an additive called pro-long. It's a co-polymer. +++++++++++++++++++++++++++++++++++++++++++++ Charles, Before you take the beast apart, you might want to check the flywheel or the flex plate if it's an automatic. A loose plate or flywheel will cause that type noise, as will rod bearings , and wrist pins. Mains don't usually make noise, but do lose oil pressure. Also take a look at ALL of the spark plugs to see if they are intact. With the low quality gas lately, it's not uncommon to blow the ceramic off the electrode and have it hammer around in a cylinder until it either ruins the piston or leaves through the exhaust. The engine will still run well if this happens as the center electrode stays in place and still allows spark jump. Piston slap is common to the R-1, because of the autothermic pistons, but this goes away after it warms up Specs for your engine with 20k or more miles should have the idle oil pressure at 15 to 17 psi, with 45 psi above 1500 rpm. The 70 psi cold was almost normal, but the relief valve should have opened at 60 to 62 psi to protect the engine. When cold, the R-1 (all R series) needs high volume, not high pressure. This is the same for our racing Fords we build right now for the road race circuit. 10w30 is actually too light for this engine, especially with the new formulations. You really should run a 10w30 TRUCK grade oil, such as Shell Rotella, it's the older formulation, designed for cast iron engines with multi layer alloy bearings. Additives are a NO NO!!! as are synthetic oils in this type engine unless, and this is a big unless the cam bearings and all oil seals in contact with rotating parts are changed to aluminum plated copper bearings, and Viton synthetic rubber seals. r(