What to replace R-22 with AB oil in compressor......walk in cooler

Thank you to all.
A new coil and TXV will take care of the obvious leaks.
I will go back with R-22. It takes less than 7 LBS.
This will be the quickest and most economical repair.

The owner is 74 and would like to just lock the door.
He has plenty of business; booked solid to march of 2021 and has bookings into Dec of 2021.
The Covid has driven up the price of beef in the retail stores as the shortage of USDA processing output has gone down. (either real or created) so the rancher prices has gone down.
People buy direct and have the processing done.
Our last grass fed whole beef lasted my wife and I for 2 years.
We just got the next one into the freezer.
All butcher shops here who do kill/processing are booked up the same. Many are for sale. Too much work for most people.
Hard to find good help....as of today NE has the lowest unemployment in the country...before Covid we were 3 or 4.

Just to point out that the original coil went about 30 years with minimal leakage. The present leaker was installed 7 years ago.
Perhaps thinner tubing in newer coils?

Talking to another guy in the trade, he says the same problem in gut rooms and has spray painted the coil end return tubes that might get one a couple of years.....anyone else tried this??

Thanks for all inputs.

Thanks ED, coated to protect against methane and ammonia?

You have to understand that there is no product to lose in the gut room......just the ripe smell and flies.
Barrels full of guts and other unmentionables waiting for the pick up by the rendering truck.

The cooler quit earlier this week. I could smell the result 1 block south of the box. Familiar with the situation, would have been a good time to be out of town and hand the job off to someone else.