I am completely bewildered at the amount of information in this site and am seeking some advice. I own a 2001 Nissan Pathfinder with 90,000 highway kms on it. I want to make the jump to synthetic. I live in Winnipeg so -35'C to +35'C is the range of temperature I drive in. I have access to AMSOIL 5W-30. Here are my questions: 1. is this brand/grade suitable for the above conditions. 2. do I have to do anything before switching to the synthetic (engine rinse/flush?) 3. is there anything that I can do to avoid leaking or complications. Thanks to those who respond.