I would like to hear more about the Neo oil

Does the sensor go in the upper plug hole? I think that's the only place you would get a meaningful reading.

I worked as a heavy repair auto/light truck mechanic for 20 years. That means engine, transmission, transfer case and drive axle. Rear (and front) drive axles are one of the most durable parts on a car or truck. I saw very few broken drives, even on snow plow rigs. All hold up well and the Ford 9" is indestructible. Lots of older cars are still running with the original oil! It's hard to break a ring or pinion gear even with abuse. I wonder why the change in oil specs now. Especially if it may increase drag.

Very true. In the heavy haul trucking business myself. The rear ends are very durable , and most failures are simply from driver abuse. It's very common to see the rear ends go a million miles with normal service intervals and your basic gear lube. None of these big major fleets are running amsoil, neo, redline, etc. Cars I can't see having as much stress on the rear end. Your typical car production V8 might put out 300 ft lbs of torque, and only stays there for a short time. Otherwise it's consuming minimal power to maintain a steady cruise at 65mph. Now a tow rig hauling a 12k lb boat up a long grade with today's high output diesels, I can see then getting pretty hot and pretty loaded.

However, semi trucks also have large gears, and large bearings. Unlike the bravo drive, which has small gears and small bearings. They probably need all the help they can get. Whether it be a better quality lube, different weight lube, or both, idk.

There are other oils that are just as good as NEO, so not trying to turn this into a brand debate at all. But considering NEO happens to be a marine blended gear oil, is a 75w-90 And is highly shear stable, I think it's a very good example to use here.

Measuring drive temps sounds very intriguing, however it doesn't answer anything beyond maybe give a chemist parameters of operation for said oil being used(if you were to call said oil company for a gear oil recommendation). Like anything, the bravo drive for example was spec'd with a certain viscosity oil, in this case it's a 90wt. Beyond doing oil analysis, which is limited in what it tells you from a wear perspective without teardown, we only really know one thing, what the gear oil is doing chemically and physically(remember SHEAR), UOA's are not a good gauge of wear..

Unfortunately you would need to approach this in a unscientific way by running 75w-90 and 75w-140 in a shear stable formulation, same brand, same intervals, similar usage and perform multiple UOA's, magnet inspections along with complete tear downs involving measurement of gear wear surfaces to determine which is truly superior. However if wear metals are lower in analysis of one grade over another and magnets are clean you can roll the dice and hope it's doing what you think it is.

im going to say two things but im not getting into a pizzin match so dont get all bent out of shape.first,no gear oil in the world is going to make a bravo style drive stand up to big hp engines espically in heavier boats,the physical size of the gears just wont last long in these harsh conditions,second saying mercury knows nothing about making a high performance marine engine is a bold statement that is incorrect imo.the no longer produced 1075 is a good high performance engine and the 1350&1650 are epic.

I agree completely with your first statement and will agree to disagree on the second. Even with the best lube, there are only marginal gains in longevity. But if that's 50-100 hrs more, I will take it. No more pissing matches. I think you and I got off to a bad start. You know how opinions work... Doesn't mean we need to butt heads.

Oil is to keep things in 'contact' from wearing.

As far as I know it does not keep teeth from breaking off nor shafts from twisting. LOL.

That's not completely true. Some gear oils are specifically designed for "shock loading" which absolutely breaks shafts/gears etc...we all know the issues with bravo drive design. It's a ticking time bomb with higher horsepower. But shock loading is an absolutely proven issue and is encountered in the marine environment on a constant basis.

All gear oils are not created equal, and if anyone had shown that, Ams oil probably did the best job with their report back in 2007 from a scientific and factual standpoint.

100% correct but some people think the gear oil is the problem when infact the drive itself is the problem.