you can know by looking at the temperature of the CPU with an optimizer. Generally, it doesn't exceed 4 degrees, because silicone grease is only its auxiliary function. If the contact between your fan and the CPU itself is already good, it may not be better to apply silicone grease, but if the contact between your fan and the CPU is not good, then silicone grease is very useful. So the key is to look at your current CPU temperature to prove whether there is good contact between the current fan and CPU!
Your current temperature is normal, which means that your CPU is in good contact with the fan, so it doesn't matter whether you apply silicone grease or not!
if the room temperature is 2 degrees, the standby temperature of CPU should be between 3 and 35 degrees. When it is hot in summer, the standby time should not exceed 45 degrees. In fact, if the fan is installed well, the role of silicone grease is not great. If the CPU temperature is too high, it is serious to change the fan.