My 2018 tacoma just reached 45 000 km. I have done regular oil changes. today I changed my diff (front & rear) fluid and transfer case oil. I do tow a bit of heavy materials so I just wanted to do some preventative maintenance. I was just curious to see what other fluids I should be keeping an eye on and when to change them. I’m a bit on the cautious side and like to change fluids a little earlier then recommended. If some one wants to let me know when and what they have changed like: spark plugs, transmission fluid, coolant, etc. Thanks !