Oil will not save an over loaded drive!!!

4 blade props on built engines only!!!

Get your gears cryo'd. Call the Bravo Shop. Great guys and knowledge!!

There are a lot of good oils out there but the "oh it's factory junk/they want it to break" noise is just that noise. Mercury has had on going issues with the 19/16 XR gears yanking a tooth for ages. Any flaking at all on the upper gears teeth near the toe would be cause to replace. Can't believe that gearset is now about $18XX.00 list price. Never reuse those clutch shaft bearings either. I've always preferred the 843240's (caged) over the 571 (full compliment) originals. I'm sure to invite argument over that because of the "but there's fewer rollers" line. Make sure the steel tower is not loose, sometimes happens after a catastrophic failure. I had to make a special tool for this after Mercury went to the single install tool hole tower. The lower is usually the least of the problems. Are you absolutely sure there were no Klingons orbiting in there. LoL They can hide in the oil transfer passage or even under the tower base by the freeze plug. I've seen them, albeit small, in the reservoir and line. Be sure to set the pre-load correctly too. I used to LoL at the nimrods at races loosening the retainer nut on an assembled drive. I'm sure they were also comfortable with phrases like "would you like fries with that?".

Say hello to Brett Anderson when you see him, I knew him when he worked at Mercury Racing plt#36.

PS can't really judge the oil after it ran with chunks in it

added: If the tower is loose go ahead and remove it, clean it, clean housing, apply 680 Loc-Tite (green), and torque to 180'lbs.

Stick with the merc green is what you are saying? just change it every 30-40 hours? (yes I do have a drive shower)
The 5 blade prop I do not believe was responsible for the 1st set of gears. changed the drive fluid last aug and it was burnt smelling.. also had a bunch of metal come out.. so late in the season I just refilled. that is when I put the new 5 blade on.. looked at the lower 40 days later at the end of summer.. teeth were missing..

The question now is why am I breaking teeth? and will the 5 blade continue to be a question mark for me? The case was fully taken a part and cleaned last year.. gears also.. always possible something got in there.. would something floating around break only one tooth? and leave the rest perfect?

when you say "lose tower" are you refering to the lower/upper bolts that hold them together? if so.. yes.. 2 nuts were a "bit" loose.. tighened them when I changed the oil.. 4 hours later I am done..

i think a 5 blade killed my xz drive on my 260

What went on your drive? How many hours on the drive with the 5 blade did you have? Did you repair or replace drive? and last.. did you stick with the 5 blade?

500 efi with a xz bravo, hydro 28p 5 blade. broke the upper gears and took out the case. i bought a merc reman upper. i sold the 5 blade and got a hydro 4 blade

Where did you get the reman from? i might need one

any merc. cerified dealer can get you one. i think bam marine that advertises here can sell you one also. merc. also has cpo (certified pre-owned) same one year warrenty as reman. if i remember dealer cost on a complete cpo xr is around $5300. not sure on just a upper though