Different oils in old and new AC compressors

[LJL]

Hi, I am replacing the AC compressor on a 2004 model vehicle that came with a Sanden SD7H15, and I am using the same Sanden SD7H15. Both old and new compressors are model number 7850, but there's 15 years in age difference between manufacturing dates.

The old unit says it takes SP-20 oil, and that's what is throughout the A/C system as a result. The new unit says SP-10. The odd thing is that the Sanden website says SP-15 for this model:
http://www.sanden.com/refrigerantoil.html

So I am concerned I have an oil compatibility issue. I don't want to have to flush the system if it can be avoided because the system was in good shape and only had a very slow leak that never leaked out completely. But I am not sure which oil is correct anyway. Is there some level of compatibility between these oils?

it looks like SP-15 can be added to SP-10 or SP-20 from the chart on that Sanden webpage, but it doesn't seem like SP-10 and SP-20 are interchangeable.

Any suggestions or advice greatly appreciated!

 

[Chris142]

I don't have my book here at home. But iirc that sp15 is ester. Sp10 is pag46 and 20 is pag 100. Both ester and pag 100 are the same viscosity.

All 3 types will mix without issues. If I was doing this job at work I would put ester in it. That's what sanden ran forever in these in the semi trucks.

 

[LJL]

@Chris142, that would be great news if you or anyone can confirm the compatibility of SP-10 and SP-20.

I was just reading about flushing AC systems, and it's a mountain of work do a flush correctly. I would basically have to removed everything in the AC system from the car to do it right. And just getting the evaporator out of the car would break my spirit.

 

[D.K.]

If you want it done right. Flush the system and use Ester oil in your new system.

 

[Quest]

Originally Posted by LJL
@Chris142, that would be great news if you or anyone can confirm the compatibility of SP-10 and SP-20.

I was just reading about flushing AC systems, and it's a mountain of work do a flush correctly. I would basically have to removed everything in the AC system from the car to do it right. And just getting the evaporator out of the car would break my spirit.



Obviously, you do not know what Chris142 does for a living, do you?

Q.

 

[Chris142]

You don't have to remove the evap to flush it. Since you did not have a compressor blow up don't worry about flushing things. Is the oil that's still in there relatively clean looking? Not black and full of metal?

Don't forget that your compressor has its own oil sump. You put the oil in that bolt on the side of the compressor. It works like an engine,it splashes the oil around inside the compressor. Many people make the mistake of putting the oil in the lines. That's kinda like putting your oil in your gas tank instead of your oil pan.

You should replace the dryer too.

 

[LJL]

Originally Posted by Quest
Originally Posted by LJL
@Chris142, that would be great news if you or anyone can confirm the compatibility of SP-10 and SP-20.

I was just reading about flushing AC systems, and it's a mountain of work do a flush correctly. I would basically have to removed everything in the AC system from the car to do it right. And just getting the evaporator out of the car would break my spirit.



Obviously, you do not know what Chris142 does for a living, do you?

Q.


Please re-read the posts above. I clearly wasn't questioning Chris142's capabilities, but rather referencing that he himself said he was going off of memory and may not be recalling the oil compatibility correctly since he didn't have his book with him.

But thanks for trying to make me look bad.

 

[LJL]

Originally Posted by Chris142
You don't have to remove the evap to flush it. Since you did not have a compressor blow up don't worry about flushing things. Is the oil that's still in there relatively clean looking? Not black and full of metal?

Don't forget that your compressor has its own oil sump. You put the oil in that bolt on the side of the compressor. It works like an engine,it splashes the oil around inside the compressor. Many people make the mistake of putting the oil in the lines. That's kinda like putting your oil in your gas tank instead of your oil pan.

You should replace the dryer too.


The oil in the old compressor looked ok. Not black or any debris. The AC was working great when it had a proper charge. It was taking a couple of months to leak out to the point the level was too low for the compressor to run.

2 oz of oil came out of the old compressor. I haven't drained the new one to see how much is in there. The Sanden manual for this manual says it comes with enough oil for the entire system, so I need to drain it and fill back the same amount that came out of old compressor, so I will do that.

I do have a new dryer ready to go with the new compressor.