There is an oil supply tube exiting the oil cooler/filter housing, the other end of which you’ll find attached to the top of your turbo (shown in the photo above inside the green circle) that feeds cooled/filtered oil to lubricate the bearings as it spools up to 230,000 RPM. Unbeknownst to most of us, and not mentioned in the Owner’s Manual that I am aware of, the turbo itself has it’s own oil filter, located within the hollow bolt (also identified in the photo above), that has a history of disintegrating at some point. I imagine this is an industry-wide practice to protect the turbos from engine break-in metal that has snuck past the engine’s oil filter, as well as from those that allow the oil filter bypass valve to open by not changing the oil filter when scheduled. Should turbo oil flow become inhibited by a broken filter element, or by trapped debris resulting from the filter doing it’s job, you would be looking at a very expensive repair to replace the turbo assembly.
Peter T. has learned about this issue through an Italian Alfa Romeo forum, and was kind enough to bring to my attention, that this filter bolt (also known as a banjo bolt by Mopar – thanks Mike34!; use a 17 mm socket – thanks goaterguy!) should probably be inspected during every other oil change (approximately every 15,000 miles), and replaced if the filter doesn’t appear to be in working condition. It appears that oil filter elements aren’t sold alone, but instead, a new filter bolt (#7 in diagram below), along with two new gaskets or crush washers (#9 in diagram below), must be purchased as a replacement.
⬅️ In fact if I read the diagram correctly, there are a couple more filter bolts on the other end of the hoses (#9 and #10 at the engine oil filter).
Multiair-brick filter bolt
Peter T. has also pointed out, that the multiair brick is also protected by a filter bolt, with an unspecified change interval, as shown in his two photos below. I would venture to say, that it should at least be changed while replacing the timing belt and water pump, and that the condition of the turbo filter bolt should be a good indicator as to the condition of the brick’s oil filter, and whether it might be a good idea to replace sooner than the 100,000 to 150,000 miles recommended for replacing the timing belt, so as not to “brick” the brick 😉
He has provided European (Ricambi) part numbers for the various known filter bolts:
MULTIAIR FILTER #: 55238665 ◊ TURBO FILTER #: 71769773 ◊ OIL FILTER #: 73500049
(The Mopar (U.S.) part # for the Multiair filter bolt is 68189847AA)
Driving Impressions in New Jersey, is an alternative source for the OEM multiair filter bolt: https://www.teamdi.com/product/fiat-multiair-engine-multiscreen-filter/ . Based on their experience with the 1.4 L engine, they recommend changing at 60,000 mile intervals.
Alternatively, aftermarket bolts have been developed (minus the filter element), that insure good continuous (unrestricted*) oil flow, which I’m sure are to be used with an unwritten assumption that good quality engine oil filter cartridges will be installed when oil changes are called for (so that the oil filter bypass valve is never engaged). Peter was able to locate a quality alternative product, and had his mechanic replace his filter bolt with it, so that he needn’t concern himself with this potential blockage source any longer.
These have 4 holes (instead of 2 like the OEM bolts), and inside it has NO filter .. so it can never tarnish or clog, and will always guarantee an excellent lubrication to the turbine bearings.
I’m hoping that I will be able to locate other sources for these bolts, besides a workshop in Italy.
* Iain points out in a comment below, that perhaps the restriction offered in the factory filter bolts is intentional. I can’t render an opinion on that subject, but hopefully an expert will chime in.
Or, if they are not easily obtainable (and don’t look like the clogged filter bolt in the second photo), you could simply rid the OEM bolt of the suspect filter element by cleaning it out with compressed air, and then reinstall the bolt using new crush washers, with 14.75 ft.•lb. (20 N•m) of torque.