I've been running 75w-90 SVG since the truck's had about 10'000kms when I did my first drive line fluid change. I change the fluid about every 80'000kms. My main reason so starting now is because I've switched to Amsoil 75w-85 and I want to see how that affects things.
I tow and haul over 50% of the trucks capacity often, primarily drive on the highway and live in Northern Alberta which has a climate of -40*C in the winter to +35*C in the summer. It's very dry and dusty here.
The silicon doesn't really concern me because I replaced the rear left axle bearing 3/4 through the service interval and between using super lube multipurpose grease to lubricate the new axle seal and the dust from the air despite covering the hole and wiping the shaft before reinstallation, i'm sure that job contaminated the lube to some extent.
I tow and haul over 50% of the trucks capacity often, primarily drive on the highway and live in Northern Alberta which has a climate of -40*C in the winter to +35*C in the summer. It's very dry and dusty here.
The silicon doesn't really concern me because I replaced the rear left axle bearing 3/4 through the service interval and between using super lube multipurpose grease to lubricate the new axle seal and the dust from the air despite covering the hole and wiping the shaft before reinstallation, i'm sure that job contaminated the lube to some extent.