I'm one who's "swimming in deep water" here. In other words, I'm extending my intervals to 20,000 miles. Anyone who rolls their eyes at this point need not read on. My experiences and testing may be helpful to some, however, and I'd appreciate constructive input from those with some significant knowledge here.
Running a 1.8L Toyota engine (2013 Lexus CT200h hybrid). I used to drive turbo 2.0 Mitsubishi Lancer Evolutions (yes, several) and modified those dramatically. Have one for sale in Albuquerque that makes 1000 hp at the 4 wheels. Dyno graph proven. Just broken in and then tuned. Just in case someone wants it.
I got a hybrid to change my driving and my psyche. It has worked beautifully. I drive like a grandma, only speeding my acceleration up a bit so I don't make people behind me mad. I'm a VERY easy driver on this car, make my tires and brakes last a long time, and expect to make the engine last a very long time, as well. The engine doesn't work much, since the electric motor is helping a lot of the time. I warm up the engine before driving.
I put Redline in the transmission at about 50,000 miles and I used to change the oil with Mobil-1 0W-20 and Mobil-1 filter every 6,000 miles (maybe 10k). My factory-original brake pads still have a lot of "meat" on them and rotors feel pretty smooth at 85,000 because I use the regenerative slowing of the drivetrain mostly. This is to give you a sense of how easy I am on the engine.
So, having said all that, and having three reasons for extended oil change intervals, I'm looking for some advice and input.
Filter:
I came on here today to do research before stocking my next filter. For some un-recalled reason, I switched from Mobil-1 filters to a Purolator PurOne. I had done some research and reading and decided that would be my "go-to" filter from here on. Toyota filters are high-quality as well, but I think they're more expensive, from what I recall.
I went to buy the Purolator One filter and saw the Purolator Boss filters. Didn't figure it was worth the extra money (extra $10 at parts store...usually I order online ahead of time).
I have sent my first 20,000 mi oil sample to Blackstone and will share analysis when it comes back. Filter looked pretty good and oil looked like most oil I've changed at "normal" intervals in many vehicles (including airplanes). I have little doubt that it'll be a reassuring analysis, but wanted to make certain before I continue with these 20,000 mi OCI's for the next several years.
Oil:
Interested in looking at Blackstone analysis (Mobil-1 Annual Protection was in there for 20k miles and is what I put in again). I'd be interested if, as Blackstone reports, all the oils are very similar and it really makes little difference. I am under the impression that, with extended OCI's, the added KOH (potassium hydroxide) in the annual protection formula will protect a bit against acid build-up. We'll see what the Total Base Number is from Blackstone. Any input as to experience with extended OCI's and different oils (particularly with analysis) would be greatly appreciated. Amsoil? Redline? Worth the expense? Anyone doing extended OCI's with "cheap" oil with good results? That would be truly the interesting test. Also, perhaps someone has added a bit of base to their oil after 10,000 miles ??? Sounds to me like a ripe market for "oil conditioner" to extend between OCI's.
Just so people don't think I do this 20,000 mile OCI willy-nilly, I run a Nissan Xterra and change oil every 6-8k, Mitsubishi turbos were every 5k except the high horsepower one (every 3K on straight 50w), and airplanes all get changed at manufacturers recommended intervals (based on hours of operation). Engine failures in those would be a bit more anxiety-provoking...plus, the airplanes have to run 1950's technology engines and they're air-cooled (except the Rotax 912ULS, which has liquid-cooled heads).
Anyway, sorry to go on and on, but I'm really looking forward to provoking some input from some knowledgeable people on here and I'm a detail oriented guy, but like to solve a problem fully and move on. Thus, if I can reliably run 20k mile OCI's and do it with a less-expensive filter and oil, I'll do that for the next decade.
Thank you all for reading!!