Originally Posted By: 1JZ_E46
I'll never understand the fascination with extending drain intervals to ridiculous levels like this. Expect the oil to be the consistency of gear oil by the end of your test.
Well not quite... Read through this: https://bobistheoilguy.com/forums/ubbthreads.php/topics/4445186/Amsoil_SS_5w-20,_62,000_miles,#Post4445186
Yeah, that's 62,000 miles on his same oil with top-up's. Yes, it's AmsOil, but no-one has proven to me that it's better than HD 30 for actual lubrication ... Has by-pass filtration and full flow filter in place. My take is the by-pass filtration is the key as it gets very small particulate contaminates out of the oil.
That Buick out to have room for a Frantz filter. Do a clean job on the by-pass plumbing and you can go to at least 15,000 before changing. But I'd do UOA's when I changed the full flow filter at the intermediate points ...
Buddy of mine added a Frantz to his Vette back in the day. Ran Sta-Lube 30 Racing Oil and only changed it every two years. This was in the 1970's when the oils were a joke by today's standards. All worked fine. But he had UOA's done even back then. A small block race motor was not any cheaper back then than it is now ...
If I were doing this scenario, I'd add a can of BG109 at each filter change and top-up. Would make me feel better, even if it did not re-create a full new add pak ...
I'd prolly run a 2 qt full flow filter if I were not running a by-pass. Any decent Napa Parts Store can look up a 2 qt interchange for you. If Fram makes one in Ultra that fits, it would be good because they have very good fine particle filtering. If no Fram Ultra, it would be a Napa Gold (WIX) or a Baldwin as the next best bet...
But, I personally would not do it unless I had by-pass filtration and was running an 0.050" orifice ... I'd want a lot of turn over on the by-pass system