87 FJ 60, 2f. I have a new radiator, water pump, fan clutch, thermostat, hoses , sender and bled it a couple of times. Heat is good and guage runs at about 30% when outdoor temp is 50 degrees or less. When either outdoor temp gets to 80 degrees or I run at 3k rpms (70mph) or use AC, guage runs at about 80%. Is this 'normal'? More history of truck (keep in mind I am not mch of a mechanic...learning though due to budget)....when I bought it coolant was very dirty, so had Jiffy Lube change collant and hoses(mistake #1) hoses not clamped down, but at time I dumped two containers of stop leak in radiator (mistake #2). Finally tightened hoses but damage done. On highway at rest stop radiator starts gushing onto parking lot after running at normal temp during trip. Start back and guage goes to red after a few miles (I think the stat stuck closed??) Anyway, blew head gasket before I could pull off...latent heat took it down. After head gasket replaced, temp guage ran at normal (40%) when truck was moving but at traffic lights rose up to 80%. So started with fan clutch and progressed through one piece at a time until replacing the sender got the traffic light guage reading down to around 25%. All was fine for several months until one day outside temp got back to the 60's and temp guage went back to 80% on the highway. Found out I was 4 quarts low on oil! Was not expecting so much burn right at 3000 miles since last change but added oil back to 8 quarts and helped some but guage now reads acording to the begining of my post. I am hoping for any comments about any influence this history might have had on the current situation of the guage reading about 80% at Interstate speeds or with AC especially when its how outside, or maybe this is just what old fj's do. I was thinking of selling at some point but who wants to buy a rig that overheats on the highway? Thanks everyone.