found the dipstick for the gear oil but not the drain.
how do you drain the oil??

its a 1984 7.4 formula f302 borg warner trans

and what gear oil should i use

The drain for the trs outdrives is on the port side of the outdrives case at the very bottom. It is a straight screw head drain plug located on the torpedo shaped lower housing

As far as fluid I am running royal purple 75w90 gear oil. Each outdrive takes almost 4 quarts. Be prepared, the oil is a little pricey! $156 for a case (12 quarts)

Make sure you purchase a merc fluid pump as they recommend you fill the drives from the drain hole to force any air bubbles out as your filling.

Good luck!

thanks again .. someone said to take the top cap off dump 3qts in there then fill the resovoir up.. which way is better?

I drain from bottom and remove cap to fill. Let it settlle and rotate prop shaft couple times to make sure all raped air is gone. Inspect large O ring on cap and put a little never seize back on bolts. dont overtighten. I use the Merc racing stuff I get in 5 gallon bucket. Good luck

Mike

Drain and fill from bottom , don't forget to watch the reservior and aslo open it ..do not over fill .
To get all the air out ..hand rotate the shaft while filling in between some pumping !!!!!!!

To each his own I guess. My only worry would be that if the drive was old and not apart for a long time you could wind up snapping off one of the bolts. Then you easy oil change turns into a night mare.

thanks for the advice!

When I filled mine I filled from the bottom drain plug but also removed the drain plug near the top of the case. When fluid came out of this hole I knew I was close to full. I put the top plug back in and another 3/4 of a quart and she was full!