I recently found engine oil in all four exhaust pipes. Engine has only ran for 10th hrs. I'm using 100 ll with aeroshell engine oil. I did the compression check on all four cylinders and the pressure cane out to 9 bars. I didn't exceed any CHT, EGT oil pressure limits during this 10 hours.I removed the exhaust pipe on one the cylinder to take better look and it seems like its leaking from exhaust valve guide. Not sure. Please help.