Does type F fluid have any different appearance than the later type fluids? I lost some fluid when I popped the dip stick fluid out of the transmission. I need to top it off and do not know what is in it. It is a rebuilt C6 that was done in around 96. I have not been able to find out what was put in it after the rebuild. The fluid is red now.
ALL FORD ATF IS RED - I have scene aftermarket fluids be green/purple....but mostly red. Note that most fluids are tinted for identification only. I have run 5w20 in c4/c6 trans before with great success.
I beleive Mercon is rated at 5w35, so 5w30 is going to run in it also.
I use Mobil 1 for this application. Motor oil (especially mobil 1) has more heat absorbtion capabilities and lube properties compared to Type F. It runs just fine, doesn't slip clutches. I would use it for HIGH stall C4/C6's over Type F. I would use mercon5 for performance AOD/E/4R.