ISX and Bypass Oil Filter Systems

[45RVLSX]

Rawze, quick question-my diesel tech was concerned about adding gear oil due to the sulfur in gear oil causing a corrosion issue. What are your thoughts about the sulfur being an issue. Full disclosure this is an ISX in a Motorhome, not an over the road truck, so maybe that makes a difference-less miles, longer time duration between changes-generally 1 per year based on typical 12-15,000 miles( I get about 7 mpg-maybe a tune would help both issues, but not sure there's a payback at my miles/yr). I'd like to do the best thing for the engine as I don't plan on replacing this motorhome in my lifetime-I'm 70 so this is my last one. My LSX typically runs around 207 degrees going down the road, does this seem ok? My LSX is a pre def unit with EGR, does a bypass make sense for this engine? Thanks for this forum, who said you can't teach an old dog new tricks!!