RT...I understand I need to get the fluid warm/hot before I start changing it but I was thinking by the time I drop the pan, change the filter and clean the pan etc. the fluid would be cool and bypass the cooler etc. But if I understand you correctly this shouldn't be a problem...right?Really, the fluid should never bypass the cooler. There is a pressure valve between the two lines that allows fluid to bypass the cooler if the cooler pathway becomes obstructed. I think some people see the reverse flow when cold just because of the fluid viscosity when cold. I would suggest getting the fluid above 100° would be sufficient for the fluid change.