Have you found a good place to source 5w-50? It's hard to come by

 

Indeed they're hard to find. I ordered 4 cases last year when NAPA was having a sale on Mobil 1 for $5/qt. IIRC. My local NAPA store didn't have any but they ordered them for me.

The 2 cases I received yesterday were bought on Amazon. Mobil 1 is having a rebate program through select online merchants including amazon.com. Let me see if I can dig it up......:

Mobil 1 0w-40 $12 rebate
Using Amazon at $34.40/6, total comes to $5.73/qt mailed to your front door.

1-1&keywords=0w-40+mobil

Mobil 1 5w-50 $12 rebate
$6.76/qt. shipped.

They increased the sale price on 0w-40 so that's why it's cheaper.

 

My local auto store had 5W 40 M1 sitting behind the counter, I had to ask for it and they went back and brought it out. It's labeled as Synthetic for Diesels.

 

Around here in PA, Mobil 1 5w-40 is relatively easy to find compared to 5w-50. Yeah, it's labeled for turbo diesel engines (and for ESP motorcycles or something like that).

I posed the question elsewhere whether 5w-40 turbo diesel oil is OK for our engines, and I never really got a firm answer to my liking. Apparently 5w-40 has higher ZDDP that can potentially damage the cats, but they "should" be OK according to one person whom others noted as being knowledgeable regarding oils, etc. I haven't yet had the guts to try it out.