is it safe to run 75/145 gear oil?
 

Hey guys I have a 03 2500 4x4 completely stock, I was doing and oil change and I thought of checking the diff fluid, I opened the check plug and it smells really bad as you might know and it had a coffee with cream color, truck has almost 230k on her, I know dodge calls for 75/90, but I hear people putting 75/110 or 75/145, I guess for towing, I don't tow but it is my regular driver so I want the most amount of protection for my drive train.
also is it safe to fill it all the way to the check plug, I can't find any record of the truck having any diff service.

Thanks.

I have used 75/145 plenty of times and even when I lived in Michigan with no ill issues. I imagine if you were in extreme cold temps you would avoid it.
Just fill it to the plug hole and you will be Ok. Some of the front pinion seals leak on those 4x4's if its filled to the drain hole so some folks keep them about 1/2" low in the front.
Milky means it has water introduced into it. This could be from condensation or a broken/cracked vent hose so check those while servicing it.

Ok,thanks.
I figure a thicker oil is less prone to break down and provides better protection, also my driving is 80% hwy and 20% city. I live in central California so no reason to worry about cold temps.
Thinking of using royal purple.
Thanks for your input.

Save your money, the Valvoline or similar is good stuff. You are welcome Sir.