10K oil changes are BAD! ??

The data is in: [2013 Lexus CT200h...Same 2ZR-FXE engine / drivetrain as Gen 3 Prius--Now at 154k miles]

Oil change at 24k was ok on analysis in 2022.
Oil change at 30k was not bad, but not optimal.
20k interval in 2020 was absolutely fine.

(Please note: If you are reading this and rolling your eyes, I understand. This car is run much more easily than most, with a relatively high proportion of highway miles, and underwent thorough EGR, intake, throttle body cleaning, new plugs, SeaFoam oil treatment (after sample taken at 24k mile interval), ATF 505 oil treatment (this time), piston soaks, etc, etc).

Couple of years running in CO at high altitudes put a bit less strain on engine as well. I ran Mobile 1 with Purolotor One filter for 20k and 24k oil changes

I was very interested to see if I could push to 30k successfully. During the past couple of years, however, been driving in TX and AZ with more dirt in the air (sometimes drove on dirt roads also...not frequently, but occasionally).

Consistent with this, the oil analysis shows more silica (this is presumably from the more dirty environment, as well as my inattention to air filter...not cleaning it anywhere near as frequently as I should have, with compressor (I use paper filters, not K&N). I should have replaced it a couple more times than I did, as well. It is likely that metal (Aluminum, Iron) would have been lower if not for the extra dirt. Regardless, numbers are pretty darn good, considering the mileage on the oil.

I lost about 1qt of oil in this last 30k miles. None was added. Car has 154k miles at change. About 1/3 of qt of oil was in catch can...with about 1/3 of that being sludge. This 30k interval was run with Amsoil Signature 0W-20 with Purolator One filter.

I'm now done with the experimenting, and hope the community may benefit from these data points: (Please note, when looking at this data, that I almost always warm my engine with no load, for at least a minute or two before driving)



I will be changing oil at a more reasonable interval now.
Not sure if I'll go as low as 10k mile changes, but certainly 20k or less. Probably would be best to go to 10k from here on (as engine getting older and now rings are more worn, with a bit more blow-by, presumably.)

My suspicion is that with mileage and wear now, switching to less expensive oil (Mobil 1 is likely way better than necessary, but certainly very high quality), and changing more frequently makes sense for 300k+ mile goal with this car. I could probably do just as well using even less expensive oil, and just change every 8k. Amsoil is no doubt very, very good quality oil, but very expensive and not needed for even 20k oil-change interval.

It is very likely that more frequent oil change is all that's needed to easily keep this engine running past 300k miles, and oil choice is 1/10th of the impact on engine wear (assuming you're not running these extreme intervals...then, it may well make a significant difference). The TBN was still 1.6, after 30k miles, so for these extremely long intervals, oil choice did make a difference, no doubt. (Amsoil has very high TBN)

This time (30k mile change), I collected the oil sample (mid-stream...adding initial drained oil back to crankcase), then ran ATS 505 Fuel treatment for 300 miles (running car up a 6000 ft elevation gain at high load with this treatment, as well as frequent full-throttle runs during this treatment. I also did a piston soak with Berryman's B12 (moved pistons a couple of times), and did oil treatment with ATS 505 Oil Treatment per instructions (2000 rpm for 20 mins).

After that, I drained oil, added two qts Penzoil Full Synthetic 0W-20 (was inexpensive at Walmart) and ran that at idle for 10-20 mins to flush all contaminated oil out, drained that, and then added Amsoil Signature 0W-20 again with Motorkote, and Purolator One Filter. Had not run Motorkote or any other oil additive in these previous samples.
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My takeaway:

Depending on how you drive (with specific attention to warming engine before driving...I use a remote start to help adhere to this), and how much dirt is blown into the air (I'm on dirt roads more than most), it is my firm belief that these engines can run very well, long-term with 15k mile oil change intervals, and ATF 505 oil treatment on changes, every other oil change. This, however, requires other maintenance to be optimal (catch can, EGR cleaning) and engine to be warmed up before driving. In my case, I spent way more energy and $ than I would have with simple 5k oil change intervals and "cheap" oil. 10k changes are a good balance, in my opinion, but I'd still do ATF 505 oil treatment before changes every other time. It could be that the piston soaks are very important, but I believe people have done 350k frequently on Gen3 engines without piston soaks. More frequent oil changes might be a replacement for piston soaks....and certainly easier. Berryman's B-12 seems better than others in Project Farm comparison for piston soaks. I suspect ATS 505 oil treatment will serve a similar purpose in cleaning rings and piston drain holes.

I do not know to what extent changing coolant helps to prevent head-gasket breakdown, but certainly EGR system cleaning is suspected to help a lot, and an oil catch can definitely helps with this system, as well (Mendel is running TWO catch cans, in series!! ). I personally recommend Purolator One filters, as they have good 10-micron filtration compared to others...however, it may not matter and even the cheapest Fram may be absolutely fine. Who knows.

I feel that the least expensive full-synthetic oil, with 10k mile intervals, is beyond conservative and absolutely great, based on my 4.5 years of of oil analysis (but run an oil catch can and do ATF 505 oil treatment every other oil change). If someone is seeing a significant difference in engine longevity, going from 10k to less than 10k mile oil changes, I believe there is highly likely to be some other variable at play. BUT, that said, my data is very significantly limited by my running an oil catch can and doing piston soaks. Am I cleaning oil passages on pistons, and cleaning varnish from rings? Is this a big part of the reason I did these ridiculous intervals successfully? It is certainly less labor and more cost effective to simply change oil frequently. If you really want a chuckle: I have a quick-release oil drain plug installed! . I recommend it, as you don't ever have to change the drain plug washer, and it's much quicker, cleaner and easier than mucking with the bolt.

My oil change intervals are the only data I've seen on this extreme interval being done with a very well-taken care of car with pre-warming engine, oil catch can, piston soaks, etc. I did this in large part because I wanted to investigate longer oil-change intervals. Certainly oil analysis is not everything, but it serves us well in running aviation engines, and certainly gives an indication of ring and cylinder wear, as well as blow-by contamination, acidity, etc.

I recommend Hengst air filters (better than WIX, and worth ordering online and waiting to get them). I had been using WIX (very good) but wasn't changing it even annually, and only very rarely blew the dirt out of it with a compressor. (I know....rather silly, considering how meticulous I've been about engine care, otherwise). It is important to change air filter more frequently, as I will do, going forward...in addition to blowing it out with a compressor from time to time, between changes.

I have just cleaned out my EGR system again (pipe, cooler, and valve), and my intake on the engine, as well as intake manifold (and throttle body). The EGR system was not too bad, which I attribute to the oil catch can serving its purpose. It may be that another significant contributor to head-gasket failures is coolant change intervals, also. Old coolant can break down head-gasket material with its acidity, from what I've heard.

Hope this has been helpful to the community to see this. The ranting about me being an idiot is expected, so don't worry if someone starts yelling about me being an idiot for doing this. I get it....but it really doesn't bother me. Just know that warming my engine most of the time likely made as big a difference as anything else, when it comes to engine wear....Does that translate into cleaner rings and piston drain holes though?

I'm really glad I did this experiment over the past 4 1/2 years (20k mile oil change in Jan 2020 with the same numbers as 13.6k mile oil change in April 2021).

 

well done, thanks!

what model and year is it?

 

Thanks. I edited the post to include these: 2013 Lexus CT200h (same drivetrain as Gen 3 Prius, with 2ZR-FXE engine). At 154k miles.

 

Great. But I expect 300K out of every Toyota I own that's not a issue the last 40 yrs or up till 2010. Seems things have fallen off sharply for all manufacturers since 2010 total mileage available to be put on vehicles has dropped seemingly almost in half engine failures have risen to the degree of Chevy citation era unbelievable but yeah all that some folks don't see any problems something see a plenty.