I have an 87 300E and it normally takes 2.4 lbs of R12 to charge the AC in these cars. I have been told verbally by a good mechanic at an MB dealer to put 80% or about 2 lbs of R134a in. (My car has already been converted to R134a) Stu Ritter in the E Class Owner's Bible says R12 get 2.4 lbs and R134a get 2.2 lbs. So should I put 2.2 or 2 lbs in? Does it make much difference anyway? Is it safer to underfill than overfill?