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Auto air conditioner oil compatibility ?

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Timelord

Mechanical
Dec 18, 2002
454
My R-4 compressor in my 93 suburban died badly so I have to clean & flush the whole system and replace all the appropriate parts. I have enough R-12 (bought when it was $2/ lb) to redo the system as original. What I need to know is if there is a GM approved oil that is compatible with R-12 & R-134A ? My thoughts are that I will benefit from the increased performance of the R-12 for a couple of years if I get the system leak tight, but if I develop a leak, or need more than 1 lb of top off (read $$), conversion with a dual compatible oil would only require recovery, evacuating and recharging with R-134A. Probably a parallel flow condenser would also be in order then, but no flushing and no two immissible oils in the system at the same time.

Thanks in advance,

Timelord
So far all I have found is that the GM recommended oil for their R-4 compressor is the 525 viscosity mineral oil. Other oils that advertise dual compatibility are lower viscosity and never mention replacing the 525 or any GM recommendation. Anybody out there an auto AC/oil expert (or maybe a GM person who knows)?
 
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If you have to replace the compressor, you should stick with the R12/mineral oil combination. There is anecdotal evidence that compressors run with R12 and then converted to R134a last longer than new R12 compressors put into an R134a environment. Down the road, if you choose to convert to R134a, your compressor will then have been "broken in" on R12 and mineral oil.
 
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