On both the MMM and the blower... Yeah, that's a gearbox, and needs gear oil (GP 90, etc).
Hydraulic fluid, if that's what you put in, is far too lightweight. Get it out of there.
Actually, the hydraulic transmission fluid and the 80W-90 gear lube, are about the same viscosity.
The transmission fluid, and the gear oil are measured on two different scales. So, people tend to mistakenly believe the gear lube is thicker.
Viscosities vary widely by brand, but both are about 30W on the motor oil scale.
Both products are in fact, light weight gear oil. The big difference between them is the additives.
The transmission oil doesn't just have to protect the transmission gears, it also has to operate the hydraulics, and the brakes. So, it has additives for all those to work better too.
The hydraulic transmission oil is designed to work in gear boxes like the front differential, or a gear box. But, those hypoid gears are best protected by EP, (extreme pressure), rated gear lube, that's what it was specifically designed for.
Look for that EP designation when you chose your product. Not all gear oil is rated that high.
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