high temperature of low pressure element Atlas Copco ZR5

Hi

We have Atlas Copco air compressor model ZR5, the design values said, in standard condition, ambient temperature 20'C, the LP outlet should be 157'C. the ambient temperature here is 38'C and temperature of LP-element show 200'C. In loading to unloading state, the temperature increases between 10 to 18'C for few time then decreases. the shutdown set in 220'C. Problem when occurs that the compressor overhauls in 8000h, the temperature of LP outlet goes to 210'C and in loading to unloading get more than 230'C and get trip. How we can resolve this problem?

We replace the oil, with similar oil in viscosity, may it cause the problem? may we need to check oil heat capacity? May it due to HP outlet check value?