A few days ago I managed to damage the oil cooler on my Bimmer. I figured that this would be a good time to upgrade the cooler and went down to the parts store and picked up a nice 17 x 10 7-pass cooler. I was about to modify the fittings to use the stock hoses (the cooler came with hose clamps to secure the lines, I just don't trust that) when I had a thought. There's probably a good reason besides "because we can" for why BMW used such big oil cooler lines and the tube in the stock cooler is so large compared to every aftermarket one I found. On the chance that it was a full-flow cooler and that my aftermarket one would be severely restricting oil flow through the engine I boxed it back up, returned it, and ordered a stocker from a BMW salvage yard. (nearly $400 for this damned thing from BMW, almost $200 from Pelican!)

So on to the question: Is the cooler full-flow which makes using anything with smaller hoses/tubes a dangerous restriction in engine oil flow? Also, is there any aftermarket cooler with high enough capacity that doesn't cost as much as an entire engine would have in my Camaro days?