Recommeded gearbox and rear oil for 1275

My manual says to use 20/50 oil in the ribcase and 90 in the rear and 
steering rack.  Is this what you guys/gals are using?  Its all set to go 
after a lot of winter odds and ends work.  Before I set it down I may as 
well do the fluids.

Do you stay away from oil with detergents.

Is it bad to fill the steering rack at the top by removing the bolt or does 
it need to be done through the zerk fitting?

Thanks a lot.  Now if the weather cooperates.

Phil Nase
http://home.ptd.net/~nase