fitted my cooler today and did oil change but?

[Jonesy]

You shouldn't need any sealer on the threads that the hose connects to. You may need some on the thread that screws into the cooler, if its tapered. But i think it will be a paralell thread in which case a copper washer or dowty seal should be used.
You may need new fittings aswell as hoses, depending on how the threads are now.

 

[Godzilla]

I will be doing I think going to get new mounting kit also as that's bent now to fit ontop ,but if anything it will be the thread on the cooler that would be worse as it's weaker than the fitting ,