It's the temperature of the engine that burns off the impurities, including any unburnt gas which ends up in the oil pan (look up "FORM" = Fuel Oil Refresh Mode).

With some PHEVs some owners are using radiator covers to help get the engines up to a high enough temp to burn off this gas in the oil during winters.

Some vehicles monitor the amount of gas in the oil and recommend changing the oil due to the amount of unburnt fuel; the 2023 Grand Cherokee 4byE is one (if memory serves).
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As I understand it, hybrids generally have a management system that warms up the engine faster than a traditional ICE vehicle, so I don't think you need to compensate for it. That's just my understanding though. As such, I'm not sure you'll get a definitive answer to your question, at least to the extent that it makes a difference, in the same way that there's no definitive answer as to whether 3k,5k,10k etc oil changes provide any real world advantage or cause harm.

For what it's worth though, according to service records, my RX hybrid appeared to do short trips/low mileage for around 50/60k prior to my ownership, and the oil was replaced annually. It even appeared to have missed an oil change during Covid, somewhere between 60k-90k, where mileage had increased significantly. The dipstick is clean, the two oil analyses I did since taking ownership came back fine, and at 110k the car runs like new, without losing a drop of oil between annual changes.

Of course there'll be anecdotal stories of early failures or long lasting cars, with oil changes at either end of the spectrum, so that doesn't help much either. What would be most useful would be some real world statistics on engine failures and oil change intervals, but I'm not aware of any. The nearest you might get is a comparison of engine failures between Europe, where 12 months/10K miles is the norm and the US, where 6 months/5k is more common, but I suspect that would be hard, if not impossible to find also.

Factor in the different types and quality of oil, whether people let oil run too low or otherwise poorly maintain their car, along with different environments, driving conditions, styles and usage profiles, and there's no definitive way of telling many of these things. As a result, the only thing anyone can do is take the manufacturers recommendation of 12 months/10k for normal usage, and 6 months/5k for severe usage as a starting point, and decide from there what you feel is best.

In other words, do what works for you and makes you happy.

True. Short trips is always hard on oils but most new engines now have sophisticated coolant systems that heat engines up much quicker now to reduce emissions.

Did that. All responses seemed to be for Jeep/Stellanis vehicles.

Does Toyota have such a mode? I know some other cars (GM) do.

A quick Google didn't link to a management system for Toyota hybrids, for me. Waiting to be educated.

I have noticed when I turn on my 350h in the morning, right away the engine temp shows one bar rather than completely cold with zero bar. So, maybe hybrids do have a system to keep warm or warm up the coolant/ engine quickly!

The nearest Toyota specific thing I could find with a quick search was this:

"Toyota has developed a heat recovery system that uses spent exhaust gas to speed up the warming of engine coolant. A new dual-passage cooling system has also been adopted to reduce the volume of coolant flowing through the engine, helping the engine reach optimum operating temperature more quickly. Because a warm engine can be shut down earlier by the hybrid system to save even more fuel."

https://mag.toyota.co.uk/pillars-of-...hybrid-system/

Mine is the same, one bar. I am sure it is the lowest the gauge can go so even if the engine is cold soaked below freezing, it would still show the one bar. There is nothing that keeps them warm but after the engine is started, it only take a few minutes and it is up to full operating temp.

The below video explains why prefilling an oil filter is a good idea. I believe the oil filter on an RX sits horizontal so filling it full would make a mess. I suppose you could fill it like 1/3 full which would be better than completely empty? Any thoughts.

Several of our current fleet have nearly horizontal oil filters. At least one maker recommends to pre-fill the filter. That will reduce the time that the engine runs relatively 'dry'. 1/3 to 1/2 full, with a quick spin-on, will contain most excess oil.

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Be happy your filter isn't positioned the same as in our first car: a 1962 Rambler Classic. The filter was a factory-added feature.

‘I remember our Rambler well!

The VW/Audi EA888 2.0liter has it's cartridge filter on the top like that. I love it because I don't need to lift the car to do an oil change. I use an extractor to pull the oil out through the dip stick tube, take off the canister cover, insert the new filter, screw it back on, fill with oil and done.

While that set up is very convenient, the engine runs dry longer at 1st start up than a horizontal or upside down filter.

Except when it incorporates an anti-drain back valve like the EA888.

Isn't it the case that Toyota hybrids prelube the engine before starting it. I don't recall the exact process, but I remember reading somewhere that it's something like the ICE being initially driven by the electric motor, with ignition only ocurring once revs rise and the engine is prelubed, thus avoiding the start up wear of traditional ICE cars.

Please watch this video:
Don't run 10,000-mile oil change intervals unless you are meeting the operating conditions set out in the manual! Most people do not meet the 10,000-mile extended oci.