I have a 1995 Z28 that finally lost its original R134 charge. I put in three cans of R134 and now it cools well again. But, I would also like to add some oil. There are two choices , and I think that the wrong choice could be damaging. So which is it, Ester or Pag , and what is each for? Also, just in case the charge goes away too soon, what are the common leak locations and the usual repairs? thanks , edman

 

PAG 150...... Ester is used when changing from R12 to R134A....

As for leaks, usually the seals around the dryer(accumulator), and condensor..