Well, I have both senders, unfortinately, I didn't have a chance to switch between them. With the oil thermostat, what are you guys seeing for temps after a short cruise? I'm thinking that all the oil is going to the cooler which is why they are so slow to rise.

Cord, I'm using the Permacool stat along with a large Eddie oil cooler. 6qt oil Pan. I use 15W50 Mobil One. Oil temp sender is in the filter adaptor before the cooler. Water temperature barely registers at 110-120, even with restrictors. Engines are home-built 502 blower motors. When cruising (3500rpm) I see 215 degrees all day long, but it takes a few miles to get there. Hard runs it bumps to 230-235.

Ok, then I'll get out and run her again. Now if somebody would please turn the heat back on?

Even with a t-stat it still takes awhile for the engine oil to warm up. The the Perma-cool stat does not close completely, thus allowing much of the oil to go through the cooler as well as back to the engine without being cooled. I was surprised by this when I got mine and looked at it. The installation instructions even mention this. I kinda wonder if it is even worth it to use a t-stat. I have it now so I'll keep it but, I would like to see the difference without it. I'll bet it is not very much.

Based off of my experience, there would be almost no difference.

With the stock merc cooler for a 502 mag 2 x 13 ( 2 x 10) is for the 454 mag) I see oil temps of 240-245ish depending on day with sender in the remote filter block after a long hard run @ 5000, 230ish running fast cruise (4000 rpm) 210ish easy cruise (3200 rpm)