I am somewhat baffled, a battery blanket and glow plugs are referring towards the motor oil. Your query is about the 10w-30 made use of as hydraulic oil in older equipment. Of course, 10w-thirty was and is still applied my lots of machines of that period even in the cold. https://do-spoilers-on-cars-do-an62738.dailyhitblog.com/32680748/5-simple-statements-about-types-of-hydraulic-fluid-for-bobcat-753-explained