Are compression fittings too PSI limited for an oil system?

I'm about to buy some components to make the hard lines for my dry sump system, and I was planning to use AN to hard line adapters from JEGS like these:

You'll notice that it says there is a max PSI of 55. I plan on using -10 AN fittings and 5/8" tubing for the hard lines. The hard lines will only be for the low pressure oil going to and from the tank before it goes to the high pressure side of the pump. I can't find specs on low pressure-side pump ratings, but I'm thinking with the decently large size of tubing I expect to use I should be OK. Any thoughts?

If you're talking about the line from the tank to the intake side of the pressure pump that'll be fine.  That's the suction side and the pressure that the fitting fitting sees can never exceed atmospheric.

If you're talking about the line from the scavenge section of the pump back to the tank that's less clear.  You've got multiple pump stages each one capable of moving large volumes of oil at well over 100 psi.  It's true that they're feeding into a pretty large hose that theoretically has little to no restriction but the capability is there.  In operation the scavenge pumps are often pumping mostly air but there are occasions where multiple stages can get big slugs of oil and try and push it all through the single line at one time.  I've never measured the pressure under those conditions but I wouldn't be surprised if it exceeded 55 PSI even if it's only momentary. 

For what it's worth I always well the fittings onto the hard lines.

Noted, thanks. When I've started the car before I seem to remember seeing oil pressures around 60 PSI. I thought that maybe the extra diameter in the lines would reduce that, but looking at the remote oil filter arrangement it appear that it is at 10-AN as well, and that appears to be where the oil ressure sender is, so I'll have to find another solution. I only have a mig welder but maybe I can weld some airtight welds. I can probably find someone to TIG them for me if I need to.

Steve, note that the fittings you show are aluminium, you can't weld those to a steel hard line, just FYI!

I wouldn't trust my mig welding on a high pressure line, I would have someone more skilled than me TiG them together.

To find that guy, ask any of the custom/race car builders in the area, they'll know who to send you to. Or go to a car show and find the most modified car there, and ask the owner who did their fab work. If they did their own then you know how skilled they are and they might take on your project for you, if they paid then you know how well the guy did for them and you can ask for his name and number.

That's how I found the guy welding up my aluminium gas  tank for my hot rod right now.....ask around.

Compression fittings as pictured are fine on fuel and oil lines. Ideally you'd grab the $40 flare tool and hardware on Amazon and do it "right" 

People have been doing it forever but I can't get behind welding fittings on thin metal lines 

That would be fine for the low-pressure/suction side, I wouldn't use them on the high-pressure side.

AMiataCalledSteve said:

Noted, thanks. When I've started the car before I seem to remember seeing oil pressures around 60 PSI. I thought that maybe the extra diameter in the lines would reduce that, but looking at the remote oil filter arrangement it appear that it is at 10-AN as well, and that appears to be where the oil ressure sender is, so I'll have to find another solution. I only have a mig welder but maybe I can weld some airtight welds. I can probably find someone to TIG them for me if I need to.

There's a pressure relief valve on the pump section that feeds the engine.  There isn't one on the scavenge sections the pressure is whatever the pumps can build against whatever resistance there is through the -10 line.

Someone mentioned using a flared fittings.  That's a good option if the line you're using is soft enough to take a flare and you have a 37 degree flaring tool that'll do a line that large.

Flared AN fittings are easy to do and good for hundreds of PSI in aluminum and thousands in steel... 

You do need a decent flaring tool. I've had good success with this one: https://www.aircraftspruce.com/catalog/topages/flaringtools2.php

I get my fittings from Aircraft Spruce as well... 

Just don't forget the tube sleeves when flaring for AN fittings! Summit Racing's flare tool works perfectly fine in aluminum, not sure if i've tried it on steel. 

It seems odd that those are only spec'd to 55 psi, pretty much all 5/8 comp fittings I find online are rated for 150-200 psi, am I missing something here for why the above fitting is so much less?

I just bought a flaring tool online yesterday, when it shows up I'm looking forward to putting all this stuff together. thanks for the suggestions everyone!