Oil coolers can be cleaned. I know this because I have had several aircraft
oil coolers cleaned and yellow tagged (that means overhauled and approved for return to service) over the years. Don't know about sending your car's
oil cooler to an aircraft overhaul facility but I can't see where it would be any different. However, I don't think you are going to get it cleaned for significantly less than the $120 that others have stated for the cost for a new one. It can be done but I doubt the financials make sense to do it.