For those of you with high millage (200k+) engines, what brand of oil do you use and do you use synthetic, blen, or petrolium based oil? i'm about to start using mobile 1 10W-30 in my 89 EF with 238k on the original motor, just wondering if anyone had any insights or suggestions. do you think 10W-40 would be safer if i run it hard? i'm not gonna worry about smoking or leaking unless that actually comes about in my car. i've already read a lot of great info on honda-tech i'm just wondering people's preferences.