In my experience, the OEM cooling is good for stock rigs with stock tires and no additional weight, etc. In other words, mall crawlers, soccer mom duty, running errands.
Once you add in extra weights, larger tires, etc. The stock cooling is marginal at best given all components are in working...
IIRC, the blue fan clutch and others will not work on the FJ80 w/ 3F-E motor. Go with the Aisin (OEM) hub (green hub), and drain and fill with 15k or desired thickness oil from any hobby store. If adding thicker oil is not enough, you can also adjust timing on the clutch to open fully at...