Brushed motors with built in fans

[Kowalski86]

I've been shopping motors and I've noticed that some of them have built-in fans, do these help with cooling to any noticable extent?

[Andylincs]

I’ve ran 21t motors with and without internal fans and not really noticed a massive difference in temps. Hard to say really as I run external fan regardless when racing. 
 

core rc motors are decent motors with fans built in (these tend to be our races go to motors for the majority) last a while and less than £10 each. Can’t fault them.