I have heard that when our trucks are placed in park the pump in the transmission does not circulate fluid through the trans lines and cooler. Only when the truck is in drive, netural, reverse or gear 1 &2. Is this true! I have heard 50/50 on this issue. I am dying to know this answer. But yet it says on the trans dip stick to check the fluid level while in netural right?

 

that is true.

checking fluid in park can give you a very false reading.