i bought some mobile 1 oil 10-30 for my car i live in sacramento california where its mainly 100 here. will this oil be ok or should i run 5-20 or is it 10-20???? also should i put 4 quarts and 1 quart of oil or stick with 5 quorts of mobile 1? one more thing my cars a 2000 with 78000 miles.