I've learnt a few things since joining this forum, most recently the fact that R134a was invented back in the 1930's a couple of years after R12, by the same bloke, which was a bit of an eye-opener for me as I thought it was invented quickly to take over from R12 in the early 90's. My question is why do we need to use POE oil with R134a as it didn't exist back in the 30's & I'm a bit of a sceptic