alot of people say use hdeo,s how much better are they then Castrol GTX 10w30 .OR ARE THEY?? does anyone have any stats to support that hdeo,s are better than Castrol GTX 10w30.if anyone can provide stats to compare rotella and other hdeo,s i would love to compare them.can anyone get info from the engine oil evalulator site or other sites so i can compare.this is for auto engines,v8 boat engines, and air cooled motorcycles and garden tractors. thank you for the help.