I have quizzed several
oil "experts" and the consensus was this. 30 weight standard
oil for a 500 mile break-in. Replace break-in
oil but leave filter. Strain break-in oil looking for metal fragments. Small amounts of fine powder type metal are no concern and actually expected. Check your magnetic drain plug if you have one. After 3500 total miles it's time to decide on
synthetic or mineral. If you want to use
synthetic, Mobil One 10-30 is what was recommended to me several times. Valvoline 10-30 was the favorite mineral. Most all agreed that
synthetic is superior to mineral for one main reason. The oiling is immediate down to way below any temps driven in a cobra. Mineral oil needs at least 120 degrees to begin oiling at the top performance of the synthetic. NEVER hard accelerate any engine until operating temps are reached.
Oil coolers look great, but are not usually needed. Hot oil is essential to good lubrication. If you install a cooler you must use a thermostat. No different oil viscosity is required when using a cooler. If your oil temp is more than 20 degrees greater than your water temp there is likely a problem and a cooler may be the resolution.