I do run an big Mocal oil cooler and I removed the small stock Si oil cooler since it was a potential failure point. I found my oil temps were a bit high with a smaller 13-row cooler when I got my close ratio tranny (much smaller power band and more time spent in a smaller rev range) and upgraded to a pretty large unit. That said, I have it mounted in front of my radiator so there is a bit of heat coming off the cooler that also passes thru the radiator. I run a Moroso baffled 5.5 Qt pan with a stock wet sump pick-up and no accusump.
Both Bob & I ran into the same problem running 'old' radiators that were several years old and it seems like these plug up with corrosion over time which causes them to run hot. We both replaced our radiators with new stock units and they work fine. I found I did have to modify my T-stat in order to get decent temperature regulation. I originally tried an OEM Honda stat but it ran just a tad warm when I upgraded to GP (bumped CR to 11:1). I tried a plain restrictor but it ran too cold and was difficult to regulate. I modified a Stant T-stat by drilling out the air bleed pin and adding a bunch of holes around the perimeter and this seems to be the best compromise.
FWIW - I also run plain distilled water + water wetter.
And yes, I've seen how much tape Bob & Jim run on their GTL cars. These were originally designed for GT3 motors, but now that they are running in GTL trim with a 24mm inlet restrictor and won't rev past 7000 rpm, they have plenty of cooling capacity. When I run in the spring or fall in cooler temps, I have to add quite a bit of tape to the grill to get enough heat to run.
Last weekend at Road America I had no tape on the grill and it was in the mid-80 degree temps and I saw 170 water temp and 210-220 oil temp (measured at the pan).
Honda & Modine make really good cooling systems!
