Toyota / Lexus A25A-FXS Hybrid engine oil questions

It was pointed out on another forum of an UOA for a Rav4 Hybrid (short trips) which has the same A25A-FXS engine as my car. I was really surprised of the high fuel dilution of 5+% and 2.2% with only 4,978 miles and 3,106 miles of oil usage respectively. Didn't expect that from a hybrid which probably had only about 70-80% of that mileage running the ICE.

Apparently a 5-6% dilution will lead to a 25% drop in viscosity. So a 6% could easily be 0W/12 right? If that's the case, keeping a low fuel dilution <2.4% will require 3-4k OCI but not exceeding the Owners Manual 5k recommended for "Severe Operating Conditions"; definitely not the regular 10k OCI. Maybe a few Italian Tune-ups here and there will help drop the %.

View attachment 256978
A good example of why one cannot automatically assume just because it’s a hybrid that the oil has an “easy life.”
 
If that's the case, keeping a low fuel dilution <2.4% will require 3-4k OCI but not exceeding the Owners Manual 5k recommended

Fuel dilution does not seem to increase linearly, it seems to spike up high quickly and then settle. You cant really say without UOA that if you cut OCI by half it will cut fuel dilution in half.

Yes, fuel lowers viscosity. Thats why many of us step up a the grade just to mitigate effects of dilution
 
Is it correct that you live in Puerto Rico, scubapr?

It’s not as if you’re seeing crazy cold temperatures inducing condensation.

It’s a catch-22. Engine temperatures don’t get hot so I want to run thinner oils for better lubricity/flow but significant fuel dilution is occurring at low mileage and so you feel tempted to run a thicker oil.
 
Is it correct that you live in Puerto Rico, scubapr?

It’s not as if you’re seeing crazy cold temperatures inducing condensation.

It’s a catch-22. Engine temperatures don’t get hot so I want to run thinner oils for better lubricity/flow but significant fuel dilution is occurring at low mileage and so you feel tempted to run a thicker oil.
Yes, I know! But it's the Caribbean; so it's also very humid.

So far I'm keeping my 6mo/5k OCI to minimize fuel dilution/water condensation. Since I'm low mileage driver my 6mo/5k OCI is actually more like a 6mo/3-4k OCI.
 
Or skip the six month silliness (Oh! We’ve been in the Caribbean for four of the last six months and we drove 1,100 miles during the other two months. It’s time to change the oil!!) Seriously??

If you’re going to waste your money doing that every six months, add up your total cost for an oil change for one year and use the cost from the two OCIs to purchase Amsoil or HPL 0w-20 and change it once per year or at just under 10k miles, whichever comes first.

The piston rings aren’t going to stick with either of those oils and you get high quality wear protection (HTHS of at least 2.7) and CLEANING.

I have your exact engine in a Toyota and I’m quite comfortable with HPL every warranted 10k miles.

If you don’t want to spend the coin on either Amsoil or HPL, I would use 5k mile OCIs, regardless of the time frame, and either Valvoline Restore and Protect 0w-20 or Mobil 1 ESP 0w-30.

I have three more OCIs worth of HPL 0w-20 sitting on the shelf at which point I’ll use the 5w-30 version.

Happy motoring!
I have been using the 5W-30 Valvoline Restore and Protect for the last 5 oil changes ( at +/- 5000 mile change intervals). UOAs are showing great results of less than 5ppm per 1000 miles, and still trending down, after starting at around 9ppm / 1000 miles . The slightly elevated aluminum and silicon wear metal numbers ( but of concern to me) were what convinced me to quit using the spec'd 0W-16 and switching to 5W-30. The vehicle had been an Avis rental car, so I doubt that Avis followed the Toyota recommendations for break in of the engine.
 
Is not 5W-30 too thick for this engine? CCN advises against such because the electronic variable oil pump is calibrated to 0W-16. (View minute 6:26)
 
Is not 5W-30 too thick for this engine? CCN advises against such because the electronic variable oil pump is calibrated to 0W-16. (View minute 6:26)

Lol no. No oil pump is “calibrated” for a grade. That video has been discussed here several times and is full of error.

The only time an oil is too thick is when the winter rating is inappropriate for the starting temperature. You can use a -30 grade all day long.
 
I remembered 0W-20 for other countries but not 5W-30. Didn't know that video was discussed previously.

It did make sense as anything that is suppose to perform variable fluid pressure has to take into account the liquid viscosity. A water pressure washer will not make the advertised PSI pumping a 5W-30 motor oil; and will definitely fail prematurely.

Anyhow, I don't think the guy is necessarily clueless. Maybe it's a general (reasonable) advice for the majority of people who don't research and perform UOA.

Good to know about 5W-30. Thanks! (y)
 
It did make sense as anything that is suppose to perform variable fluid pressure has to take into account the liquid viscosity. A water pressure washer will not make the advertised PSI pumping a 5W-30 motor oil; and will definitely fail prematurely.

Anyhow, I don't think the guy is necessarily clueless. Maybe it's a general (reasonable) advice for the majority of people who don't research and perform UOA.
People who do not understand what they are talking about should not be in the business of making publicly available YouTube videos where they categorically state falsehoods. He's either making that stuff up or is regurgitating something he heard on the Internet. A UOA is useless here.
 
Is not 5W-30 too thick for this engine? CCN advises against such because the electronic variable oil pump is calibrated to 0W-16. (View minute 6:26)

My argument is not with you, it's with the argument that somehow this oil pump cannot regulate oil pressure. After all 5W 30 at some combination of temperatures is going to be the exact same viscosity as 0w-16 at another combination of temps and yet the engine is OK.

So then how does it not choke and struggle at temps from -30 to 110F? Clearly it can deal with a viscosity at those temperatures. Short trips, cold starts, stop and go traffic on the interstate in Phoenix?
 
I remembered 0W-20 for other countries but not 5W-30. Didn't know that video was discussed previously.

It did make sense as anything that is suppose to perform variable fluid pressure has to take into account the liquid viscosity. A water pressure washer will not make the advertised PSI pumping a 5W-30 motor oil; and will definitely fail prematurely.

Anyhow, I don't think the guy is necessarily clueless. Maybe it's a general (reasonable) advice for the majority of people who don't research and perform UOA.

Good to know about 5W-30. Thanks! (y)
 
Is not 5W-30 too thick for this engine? CCN advises against such because the electronic variable oil pump is calibrated to 0W-16. (View minute 6:26)

CCN knows a lot of things but he is wrong about the oil pump. Also, the notion that bearing clearances are tighter on modern engines is wrong. Bearing tolerances have not changed in decades and is pretty much standardized 0.001 inch of clearance for every inch of journal diameter.

The thing that made me rethink 5w-30 was live monitoring of the actual oil temperatures showing that even after fully warmed up, oil temperature runs around 160F in stop and go driving and barely moves above 180F on sustained highway driving (engine always on at low RPM/low horsepower) and does blip up to 200F going at highway speeds up a pass. This is on 0w-16 and 0w-20. I did notice that oil warms up more slowly with 5w-30. However, I have not measured anything in summer driving, and it’s been cool around here ranging from 40F in the morning to 70F in the daytime.

This engine runs cold and after plenty of warm-up oil temperature lives between 80 and 90C. Coolant temperature is almost always higher than the oil temp and when the digital thermometer hits the middle of the bar, it’s 135F coolant temperature and the bar does not budge and stays pegged to the middle even when coolant is 200F. It just stays pegged to the middle giving you a sense as if the coolant temperature is not fluctuating at all.

Engine oil temperature measurement convinced me that thinner oils may not be damaging the engine and fluidity at the colder temperatures as the hybrid engine turns on and off is more important than high temperature/high shear protection.

CCN would convince a lot more people of thin oils if he just told everyone that the hybrid engine runs way way cooler than a standard non-hybrid engine.
 
CCN knows a lot of things but he is wrong about the oil pump. Also, the notion that bearing clearances are tighter on modern engines is wrong. Bearing tolerances have not changed in decades and is pretty much standardized 0.001 inch of clearance for every inch of journal diameter.

The thing that made me rethink 5w-30 was live monitoring of the actual oil temperatures showing that even after fully warmed up, oil temperature runs around 160F in stop and go driving and barely moves above 180F on sustained highway driving (engine always on at low RPM/low horsepower) and does blip up to 200F going at highway speeds up a pass. This is on 0w-16 and 0w-20. I did notice that oil warms up more slowly with 5w-30. However, I have not measured anything in summer driving, and it’s been cool around here ranging from 40F in the morning to 70F in the daytime.

This engine runs cold and after plenty of warm-up oil temperature lives between 80 and 90C. Coolant temperature is almost always higher than the oil temp and when the digital thermometer hits the middle of the bar, it’s 135F coolant temperature and the bar does not budge and stays pegged to the middle even when coolant is 200F. It just stays pegged to the middle giving you a sense as if the coolant temperature is not fluctuating at all.

Engine oil temperature measurement convinced me that thinner oils may not be damaging the engine and fluidity at the colder temperatures as the hybrid engine turns on and off is more important than high temperature/high shear protection.

CCN would convince a lot more people of thin oils if he just told everyone that the hybrid engine runs way way cooler than a standard non-hybrid engine.
For me when someone gets such basic things wrong, but persists in posting them as if they were absolute truth I cease to listen to the rest. Again, one should not speak on subjects for which you are apparently unqualified. That shows a lack of understanding that undoubtedly carries over into other topics.
 
CCN knows a lot of things but he is wrong about the oil pump. Also, the notion that bearing clearances are tighter on modern engines is wrong. Bearing tolerances have not changed in decades and is pretty much standardized 0.001 inch of clearance for every inch of journal diameter.

The thing that made me rethink 5w-30 was live monitoring of the actual oil temperatures showing that even after fully warmed up, oil temperature runs around 160F in stop and go driving and barely moves above 180F on sustained highway driving (engine always on at low RPM/low horsepower) and does blip up to 200F going at highway speeds up a pass. This is on 0w-16 and 0w-20. I did notice that oil warms up more slowly with 5w-30. However, I have not measured anything in summer driving, and it’s been cool around here ranging from 40F in the morning to 70F in the daytime.

Engine oil temperature measurement convinced me that thinner oils may not be damaging the engine and fluidity at the colder temperatures as the hybrid engine turns on and off is more important than high temperature/high shear protection.
With the caveat that the oil temp does not reflect the transient temp of the oil at the locations where it's likely to be the highest pressure, friction and temps. And it's exactly these spots where I want protection, vs at the oil temp sensor location.
 

Thank you very much! Very informative. I'm still learning and researching about this. I always like to know the why and how stuff works of things. Maybe it's the Engineering/Physics background in me.

I still like the CCN as he appears to be very knowledgeable and a very good experienced mechanic. But it's not his fault if people do not research, nobody is 100% correct all of the time as this thread clearly shows. Fortunately his analysis/assumption on this oil pump issue, although not 100% true, will not damage anyone's car as also follows the owners manual recommendation (at least in USA). He's still a Toyota Mechanic not a Toyota Engineer.

CCN knows a lot of things but he is wrong about the oil pump. Also, the notion that bearing clearances are tighter on modern engines is wrong. Bearing tolerances have not changed in decades and is pretty much standardized 0.001 inch of clearance for every inch of journal diameter.

The thing that made me rethink 5w-30 was live monitoring of the actual oil temperatures showing that even after fully warmed up, oil temperature runs around 160F in stop and go driving and barely moves above 180F on sustained highway driving (engine always on at low RPM/low horsepower) and does blip up to 200F going at highway speeds up a pass. This is on 0w-16 and 0w-20. I did notice that oil warms up more slowly with 5w-30. However, I have not measured anything in summer driving, and it’s been cool around here ranging from 40F in the morning to 70F in the daytime.

This engine runs cold and after plenty of warm-up oil temperature lives between 80 and 90C. Coolant temperature is almost always higher than the oil temp and when the digital thermometer hits the middle of the bar, it’s 135F coolant temperature and the bar does not budge and stays pegged to the middle even when coolant is 200F. It just stays pegged to the middle giving you a sense as if the coolant temperature is not fluctuating at all.

Engine oil temperature measurement convinced me that thinner oils may not be damaging the engine and fluidity at the colder temperatures as the hybrid engine turns on and off is more important than high temperature/high shear protection.

CCN would convince a lot more people of thin oils if he just told everyone that the hybrid engine runs way way cooler than a standard non-hybrid engine.
Thanks! That's very interesting as I'm in a hotter weather and we don't experience the freezing cold. Here the temperature ranges between 68F/20C -> 86F/30C in winter and 84F/29C -> 97F/36C in summer. Right now is at 74F/23C @ 8:30PM ET
 
With the caveat that the oil temp does not reflect the transient temp of the oil at the locations where it's likely to be the highest pressure, friction and temps. And it's exactly these spots where I want protection, vs at the oil temp sensor location.
Very true. My concern is adequate oil flow and I don’t know what the bottom barrel measured engine temperature is where theoretical higher viscosity doesn’t become counterproductive when it comes to wear. I’m thinking 0w-20 is the sweet spot because 5w-30 does lead to a significantly slower rise of oil to operating temperature. I’ll feed my engine 5w-30 in the summer and see how it does.
 
Very true. My concern is adequate oil flow and I don’t know what the bottom barrel measured engine temperature is where theoretical higher viscosity doesn’t become counterproductive when it comes to wear. I’m thinking 0w-20 is the sweet spot because 5w-30 does lead to a significantly slower rise of oil to operating temperature. I’ll feed my engine 5w-30 in the summer and see how it does.
Viscosity isn't going to become counterproductive to flow, especially not for any SAE grade. Flow never lubricated a bearing anyway, and the positive displacement oil pump makes sure there is adequate flow. What matters is adequate HT/HS under all circumstances.
 
I still like the CCN as he appears to be very knowledgeable and a very good experienced mechanic. But it's not his fault if people do not research, nobody is 100% correct all of the time as this thread clearly shows. Fortunately his analysis/assumption on this oil pump issue, although not 100% true, will not damage anyone's
It's a lot less than 100%, and it's the attitude that he's 100% sure about something for which he's 100% wrong. He really misunderstands how an oil pump works and how lubrication occurs in the engine. He also is clueless as to what happens to viscosity as the temperature changes. If the oil pump was that sensitive (or "calibrated") to a certain viscosity then those pumps would fail in short order.
 
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