I buy my oil at the local VW dealer parts department
. It is Castrol Edge Professional LL03/507.00 Spec 5W30 Engine Oil, and cost me (just bought some yesterday) about $8 a liter, $8.74 with tax. They don't make any money on it. Dealer is cheap, easy, and nearby for me. Now some dealers may tack on 50% sucker walk in retail charge. I bought my car there, and they know me. Most parts guys have authority to give you the wholesale price, or if not wholesale price they can not fully gouge you. Based on my research $10/L with tax, is a fair going price. So at $8 I am doing well. Which reminds me I need to go buy 5 or 10 liters just to stock up.
I Googled Walmart which has a case of 6 x 1 liter bottles of Castrol Edge Pro LL03/507.00, $56.88 free shipping, pick up at store. I assume they'll charge sales tax, which is 9.25% where I live. So it cost $10.35/liter with tax. The VW dealer is cheaper.
I once special ordered from NAPA a 5 liter jug of Top Tec 4200 Long Life 507.00 Engine Oil (5w-30). This is made by Liqui-Molly. I forgot what I paid a few years ago, but it is now $59 plus tax. Dealer wins again.
I see ECI sells a jug of Top Tec 4200 Long Life 504.00 / 507.00 Engine Oil (5w-30) - 5 liters for $53.49 free shipping and assume no sales tax... That works out to $10.69/liter. Again dealer is best price.
Ladies and Gents, we are going to pay about $9 to $11 Liter x 4.5 Liters/per oil change. It is good for 7,500 miles (or 10,000 if you want). There is NO CHEAP LL03 507.00 Spec 5-30w oil... It is pretty limited market. Frankly just finding this special oil can be a PIA for some folks.
I used $500 of my $1000 VW appeasement money to buy oil and filters. I recall I got 3 engine oil/filter changes worth of supplies, along with 1 DSG oil/filter change kit, air filter, fuel filter and cabin filter, with enough left over for an interior LED light kit and VW Jacket. I just did my last "free" oil change. I also did the DSG, fuel and air filter all at once just this week myself. I have nothing left of my free stuff, except one extra engine oil filter. Now I have to pay for oil next time... Booooo...
I just went to Walmart and bought oil for my motorcycle and scooter. I got 5 quarts of premium Castrol for $19. I saw Mobile 1 synthetic for $23 for 5 Qt (4.73 liter). That works out to be $4.86 a liter, half the price of our special TDI oil.
The special VW Spec oil for the TDI CR has a limited market. How would a TDI run on Mobile 1 or other oils? I don't know and don't want to find out. I pay two times the price of conventional oils like the rest of you...