My trim is making an aweful noise when I trim the motor down. When it hits the pin it stops. Any suggestions on what this might be?

I am thinking it may be the fluid. What is the recommended fluid to use on Tilt/Trim System? Someone told me Dextron transmission fluid would work. Does anyone use this?

Also, is there a good website to order gear lube, oil, ring free plus, etc. from?

Motor is 2004 HPDI 250.

Thanks,