AC oil again

[Erlend]

Please foregive the redundancy here, but my search of the archives did not answer my question:

How much and where do I put oil in a vacated ac system with new compressor? 1981 300D with R4 compressor.

My guru is suggesting a bunch in the compressor (then turn by hand 12 times) and some in the receiver-drier. He also says to use ester oil as this is going from R12 to R134a. Doesn't seem to know anything more specific for an old MB.

So, after reading the archives, I am only more in doubt: one thing in consensus seems to be that adding too much is bad. But i am not clear on what is too much.

The gist of what I've read seems to suggest 4 oz in the compressor and 4 oz in the receiver drier. Does that sound right?

[sailor15015]

That sounds right. You need to turn the compressor first because its new and has no oil in it. I've heard 6-8 oz and when I redid my system, I used 4 in the comp and 4 in the dryer. If its not too late, go with synthetic oil. That way there's no need to worry about specific oils for specific refrigerants, and its got to be better for the compressor and the R4 needs all the help it can get. BTW, I redid my system two summers ago, with a rebuilt R$ and, you guessed it, I'm having to do it again right now because the rebuilt comp gave out. Don't cheap out the $60 or so you'll save with a rebuild. Its not worth the hassle.

[vstech]

also, be surre surre surre that you have totally blown and flushed all traces of mineral oil from the evaporator, condenser and all freon lines. also replace the expansion valve and reciever/drier. now, once you have done all that, buy some real R12 and put it back the way it was. don't cheap out, 134a is junk in this system. it will not cool well, it will kill the compressor. just go back with 12.

[rrgrassi]

You need to use either the GM specified oil, or get the BG frigi-quite oil. I'm using the BG stuff. I got it from a local rep for $11.99. Much cheaper than $39.99 through Diesel Giant.