I have the 2007 Megacab in my sig. I have added some power to it, about 100hp, and it tows a 36.5' fifth wheel RV. I have noticed that at the end of every towing season, the paint on the rear diff cover seems to have flaked off the area where the ring gear slings oil at it. I have a PPE finned aluminium diff cover to install (that adds 2 quarts oil capacity). Here's a picture of one like it I grabbed off the www.
I have changed the gear oil every year, and always use the recommended 75w90 synthetic GL5 gear oil in the diff. Last time I think it was Catrol brand.
Anyway, before I take the old cover off and put the new one on, I obviously want to have the new oil ready, and I'll need 6 quarts give or take.
Looking for recommendations as to what brand to use, and what viscosity.
Some points to consider:
- The manual calls for 75w90.
- I tow 2 months a year
- I live in Canada, it gets cold here (-40*)
- truck is used as a daily commuter the other 10 months of the year
I have been considering Amsoil 75w110 as a nice comprimise between the 90 and 140. A little heavier oil when hot for better protection, but not the 140 weight. I don't want 75w140 due to cold weather performance.
75w90, 75w110, or 75w140...brand? -- Thoughts?