Had my motors rebuilt this winter and in one of them the oil temperature is running 230 to 240 while the water temperature is 180. Any help would be appreciated.

How hard are you running when seeing those temps?
Is the warmer motor also running a power steering pump and cooler?
Are both motors performing equally and showing the same oil pressures (at least up until the temperatures start to differ)?

running about 4200 RPM. Yes. And yes

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I experienced the same situation in my 35 Cigarette. I was told not to worry about it as the PS cooler was on that side and adding heat to the cooling circuit, reducing the effectiveness of the oil cooler. I didn't really buy it but after backflushing both coolers, disassembling and checking the oil thermostats, and finding nothing, I just lived with it.