i know that minis use the high grade synthetic stuff good for 15k miles. however, could you use some regular synthetic oil? what about natural oil?

one more thing, the next oil change will be the first one with my oil cooler attached. it seems this would trap alot of the old oil. but once new oil is added, this would all mix in. so i am guessing that the same weight oil is needed and that the old oil that was left in the cooler wont hurt the car, right?

 

'regular synthetic'?? I'd recommend using a high quality synthetic. You CAN use dino oil, but you forego the benefits of sythetics - longer life, better lubricating properties. Why spend $20K+ on a car and cheap out on $20 per oil change?
You definitely want to use the same weight oil. The old oil (in the cooler) will be dirty. It would be best to poor this out. Otherwise, reduce your oil change interval to account for X% of dirty oil in your clean oil.

 

walmart sells those Mobil1 5 quart jugs for like $25...

 

Mobile 1 baby

thats what i was putting in mine.

 

i'm running a cooler too . i'm gonna put a drain on it . it's one reason i bet alot of guys running coolers go top mount.