quit radiator question(will it fit)
 

will an automatic radiator from an 87 fit on my 90 5spd?????

No. You will lose your rad cap on the radiator. The S4's used the thermostat housing as their high point to fill with; s5's used a long neck on the radiator as their highpoint. Even if there is a radiator cap in the middle, you would be hard pressed to bleed all of the air out of the system as the thermostat housing would be higher than the rad cap....

Unless, of course, you parked upwards a very steep hill....
Safest bet is just to find an S5 radiator so you have the correct filelr neck. Auto or manual will be fine, the auto's just have some fittings for the tranny fluid heat exchanger.

get a Koyo from Rx7 store.
It's around $325 but totally worth it.

My car idled in 95+ heat sunday for over an hour and never went over 1/4 on the temp guage.