Here's an interesting thing I recently found out in the airplane world. When working with alluminum parts they like to use steel fittings, yes ipeven in the light weight world of airplanes the preferred choice is alluminum for fittings.
DAMAGED THREAD ISSUES
This is another area where trouble is encountered over and over again - instead of being avoided; damage to threads in aluminum oil coolers. Boogering-up the threads on most any aluminum aircraft oil cooler is enough to render it beyond economical repair (BER). Even on the rare occasion when the thread damage is minor and was able to be corrected by chasing them with a tap, the oil cooler must then be overhauled to remove any metal contamination.
Any threaded hole in an aluminum oil cooler is a place where trouble is looking to happen - especially the ones where the fittings screw into the cooler. Typically, this is a 3/8” tapered pipe thread which, as we all know, requires a slight interference type of fit between the threads in the cooler and the threads on the fitting in order to achieve an oil-tight seal. For this reason, NEVER-EVER attempt to thread a fitting into these holes without first applying some type of anti-seize compound - or even plain old Teflon tape to the threads.
Also avoid re-use of aluminum fittings. In fact, throw all aluminum fittings as far away as you can from the work you are doing - and use steel fittings instead. Steel fittings, when installed with some type of lubricant on the threads, will almost never gall, bind up, or damage the threads of an aluminum oil cooler. In addition, steel fittings will un-screw cleanly from the cooler - even many decades later. None of these things can be truthfully said about aluminum fittings.
An excerpt from an article:
Steel is the fitting material of choice if you want to avoid damaging the threads of an aluminum oil cooler. Additionally, steel fittings will un-screw from the oil cooler cleanly and with no thread damage, even many years later. No matter what they’re made of, never ever screw fittings into an aluminum oil cooler without first applying some form of thread lubrication - and use aluminum fittings only as a last-ditch resort.
If you must use aluminum fittings for some reason, make sure that the threads are clean and defect-free, use Teflon tape or an anti-seize lubricant made for use on threads, and work slowly and carefully as you begin screwing the fitting into the oil cooler (and cross your fingers, also).
old set up-3250 LBS 69 firebird T-88 turbo 455 .030 CAT H beam rods, stock crank, stock block( 2 bolt) performer intake, 850 carb 6X-6 heads 114 cc ( unported) TH 400 and 3.73 gears = 9.76 @ 141 with a 163 short time = 725 RWHP and 878 HP @ the crank
new set up - same but with home ported heads and Gen 7 DFI, my custom SS headers