I am a tiny bit baffled, a battery blanket and glow plugs are referring into the engine oil. Your concern is in regards to the 10w-thirty utilized as hydraulic oil in older equipment. Yes, 10w-30 was and is still applied my many machines of that period even within the chilly. https://brakecheckimperialpointfl31740.thezenweb.com/how-types-of-hydraulic-fluid-for-bobcat-753-can-save-you-time-stress-and-money-65009712