Probably no worse than some of the other hyped up oils out there. Results can be surprising...

I think you're leaving money on the table Mild, I'll bet you could get $21 per quart!

Back when I was running my speedies I would change the oil every other week (cheep Dino gear lube) never had an Issue, I believe that proper Maintenance will save you $$ in the long run. I still change the gear oil twice a month on my bravos and they are going on 14 years without a brg failure, and they are seeing a very large amount of HP and a very high X. I have blown the floors out twice in that time on the clockwise drive. but that's not the lubes fault! I believe in PM and then some. The high priced lube is just that. So with that said I'm ready for the crap to fly!!
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Joe i think like you. we used GM high performance full synthetic gear lube in some bravo drives with poor results. i was thinking well if GM did the research and runs the stuff in Z06 corvettes and diesel trucks its gotta work good for a bravo drive. Well after a couple drive failures the person rebuilding our drives asked what fluid we were using. i said the really expensive GM gear lube that i can get for free from work lol. he said thats the problem. the gm lube doesnt have any "tackifiers" in it and the gear lube runs right off the gears. so we switched to Quick silver high performance gear lube and didnt have a problem since. at first i was gonna declare B/S about the gm gear oil then i did my own test and sure as sh!t the quicksilver sticks to metal WAY better than the GM gear lube.

5"s on boxes and I were discussing what lube to use in our speedys. figured see what the speedmaster guys are using these days

I'm going to use the merc hi perf oil. If you buy it in a 16 gallon drum it's about $8 p/qt. and when you need 6 gallons for 1 boat...... 2 guys can split it or service a few other boats and sell it for the typical $14 p/qt

i get a kick out of guys that think some magical gear lube will stop shafts from twisting and gears from getting fatigued and breaking.some guys think a xr drive can take the abuse like a 6 drive if they use brand X lube.

I just used the Severe Gear 75w140 and it has a nice aroma. It has to be good.

Joking aside, I did just put it in. I also bought the Severe Gear 190 and I might even try it in a few weeks. It is a cool electric green color. If 140 is good, 190 has to be better right?

I use the Bravo Shop 75W90MRHD synthetic gear oil.

Running Mystic JT7 85W-140, Yes Mystic, in Mercury BlackHawks with 1:50 Gears attached to 550 Horse on each. Inexpensive enough to change a couple of times a season to check for any metals in the oil. Comes out a Pretty clear Red each time changed over the past few years. Was turned on to it by the late Brad Smith, SMITH POWER and will never change.

I have a friend who swears by the mystik gear lubes also. Readily avail and cheap at farm & fleet! So Brad liked the thicker oil? He was a sharp man and don't blame you for taking his advice .

Brad told me he had used it in a lot of the drives he and his dad worked on. There were some that would come back to them after two years of use and abuse, knowing the drivers, and the fluid would come out as red as it went in. Don't think he used it in the higher end #6's and so forth but would use what manf recommended there, after all you spend enough on a drive why would you skimp on the cost of oil (not saying Mystic is cheap but is Inexpensive and a Old Skool non marketed to death, putting money in the mans pocket product). For my BlackHawks it has been great. Brad rebuilt two of my drive upgrading gears and his dad just finished my spare (Bob "POP's" is a hell of a gear guy).