I have a recurring task set up in Things to remind me to clean my late 2013 Mac Pro. Every two months I pull off the shell and blow off the dust that accumulates inside with a bulb blower I bought to clean camera equipment. Also because I have a feline office mate, cat fur accumulates on the bottom of the unit at its fan intake vents. After a good clean iStat Menus reports noticeably lower operating temps.
A thread-locking fluid (“Schraubensicherungslack”). When disassembling devices, you often notice blue “stuff” on the screws. That’s Loctite. It allows you to secure screws without overtightening (and stripping/damaging screw heads).