Hey guys, My friend's 03 levin rolla transmission is rattling really loudly after third gear. Instead of overhauling the gears (its third, fourth and fifth), he's going to try to give changing the transmission fluid a change (it's been a while). He's just asked me what type of transmission fluid he would need, and if it would be safe to mix in something called 'Nulon G70' to help it out even more.. Is there any other things he could do that might quieten down the rattle? The car has done 150,000 and he's been roughly quoted $1500 to get it all fixed by his local mechanic. Thanks!