Hi Michael, suggest the following...
We used Chevron Delo 400 30 weight for both the engine and tranny. WM carries it and the filters. Our H28 had a 2GM and the tranny dip stick had a proper level mark right at the tip. The engine oil reservoir is separate from the tranny. The only way to drain the oil was through the dip stick hole. The best device we found for removing the oil, also from WM, is a two gallon blue can with a vacuum pump. You use its pump to creat a vacuum in the can, stick the evacuation tube down the dip stick hole and come back in ten minutes. No muss, no fuss. It is a little pricey, but worth the money, IMHO. Run the engine for five minutes to warm the oil before removing it.Terry