Engine Mechanical problem
1974 GMC Truck V8 Two Wheel Drive Automatic 90000 miles

this truck was bought from an old man that dis wonderful maintance on this truck. he always used 10w30 valvoline.
i bought this for my 20 year old son. im sure their driving styles are different.


what type oil should i use? the same as the old man or something else.

it does not leak or use oil. it was changed prior to me buying it.

thanks