Help with a Mini
 

08 Mini base, oil fouling number 2 plug, compression at 198 and leak down was 0 loss.
any help would be great

if leak down is 0...
 

The leakdown checks the rings and valve seal (valve to head - not valve stem sealing) - if 0 or low then either they are not leaking or your tester isn't working correctly - you should see a small amount of leak...
with 198 pressure I'd suspect the rings and valve sealing are good

so where does the fouling come from??? a few ideas/questions
valve seals and valve stem wear/condition - it could be a seal is worn or popped off and hence more oil is flowing down the valve

How many miles on the car?
What type/weight of oil are you using?
does it smoke when it runs?
does that cylinder have spark?

Have you replaced that plug?

i had the head rebuilt 8k mile ago.. new guides, seats, valves. and seals. car has 125k. I removed the head and sent it back to the shop and nothing was found wrong. ran fine then one day number 2 just mis fired. removed plug and it had oil on it.. this is only after the engine warmed up. replaced the plug and same issue. leak down was working i used it on my land rover to check. starting to think oil ring and scraper ring are bad. i'm using recommed oil.. car was getting 40mpg and running like great.

when i removed the head, i had no oil on the piston...