Skyhawk-N
The CAA would not have anything to say about the use of 15W50 oil because if the oil is stated as an alternative method of AD compliance then that is just what it is.
I am now going to have to go back to the club and find out what is going on as the rate of oil use is far below that stated and I need to find out why.
The use rate on the aircraft that I have direct control over is more in line with the posts above.