0W16 + 0W20 = 0W18? Mixing 2 qts Castrol 0W20 with 2 qts Toyota 0W16!

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My 2018 Camry specs 0W16. I put Pennzoil 0W20 in it. The valve-train is quieter, the gas mileage is essentially the same. Very non-scientific, but, I like the quieter valve-train...so, I'll keep putting 0w20 in it. I seriously doubt Toyota's 0w16 is performing measurably better than Pennzoil Platinum 0w20.
 
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I noticed all your mileage figures are always dash displayed readings. Have you ever hand calculated your mileage to see how accurate it is? The dash display in my '16 Nissan is consistently 4-7 mpg optimistic. You mention some of the oil in your frankenbrew being approximately a year old the reason you were going to dump it. I'm consistently using 15-25 year old oil in all my cars with no problems. I've got some Castol GTX 20w50 I used in a motorcycle in the '80s in the garage that is in cardboard cans. I'm pretty sure it's between 35-40 years old and I wouldn't hesitate to use it. I don't mix brands/weights in my better cars but have been known to on daily drivers with 100-500K miles on them with no noticeable negative impact.
 
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Lower viscosity oil is the future. I’ve got a 2012 2nd gen Honda Fit that I am running 3qts 0w20 and 3/4qt 0w16. It’s quick to start and warms up faster than the 5w30 synthetic I had prior. It’s also quieter. I don’t have the variable valve oil pump necessary to run a straight 0w16.
 
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Lower viscosity oil is the future. I’ve got a 2012 2nd gen Honda Fit that I am running 3qts 0w20 and 3/4qt 0w16. It’s quick to start and warms up faster than the 5w30 synthetic I had prior. It’s also quieter. I don’t have the variable valve oil pump necessary to run a straight 0w16.
Actually it doesn’t but that shows the power of the imagination.
 
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Actually it doesn’t but that shows the power of the imagination.
Actually it does. Lower viscosity oil does warm up faster than thicker viscosity oil. It does so for emissions purposes allowing the engine to reach operational temp sooner than thicker oils. Simple physics. Now it’s not a huge difference in warm up time between 5/30 and 0/20, maybe a few minutes, but it there. Millions of cars reaching operational temp a few min sooner and polluting less makes a huge difference collectively.
 
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Actually it does. Lower viscosity oil does warm up faster than thicker viscosity oil. It does so for emissions purposes allowing the engine to reach operational temp sooner than thicker oils. Simple physics. Now it’s not a huge difference in warm up time between 5/30 and 0/20, maybe a few minutes, but it there. Millions of cars reaching operational temp a few min sooner and polluting less makes a huge difference collectively.
Nope. Greater shear heating in a more viscous liquid leads to a higher heat load. Using thinner oils competes with a manufacturer’s desire for converter light-off which is typically mitigated by inhibiting transmission upshift while cold.

You’re missing the simple physics here. Thicker oils always heat up faster.
 

OVERKILL

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Actually it does. Lower viscosity oil does warm up faster than thicker viscosity oil. It does so for emissions purposes allowing the engine to reach operational temp sooner than thicker oils. Simple physics. Now it’s not a huge difference in warm up time between 5/30 and 0/20, maybe a few minutes, but it there. Millions of cars reaching operational temp a few min sooner and polluting less makes a huge difference collectively.
As @kschachn noted, a heavier oil heats faster because of the friction of the shearing action taking place in the bearings. A lower viscosity oil will provide less drag, which will also slow the warm-up process. However, that reduction in drag reduces fuel consumption, and that's what's being chased with the thinner oils.

Efforts to get the coolant and the oil up to temperature faster are made with coolant-to-oil heat exchangers and things like grille shutters to block air across the rad. My wife's truck has both and heats up quicker than my 6.4L, which also has the coolant/oil heat exchanger, but no grille shutters.
 
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As @kschachn noted, a heavier oil heats faster because of the friction of the shearing action taking place in the bearings. A lower viscosity oil will provide less drag, which will also slow the warm-up process. However, that reduction in drag reduces fuel consumption, and that's what's being chased with the thinner oil

Efforts to get the coolant and the oil up to temperature faster are made with coolant-to-oil heat exchangers and things like grille shutters to block air across the rad. My wife's truck has both and heats up quicker than my 6.4L, which also has the coolant/oil heat exchanger, but no grille shutters.
This is from the pennzoil website. Mobil1 web site is similar.

0W motor oil was developed to operate in today’s modern vehicle engines, which are smaller and run hotter than older engines. In order to make a 0W motor oil, synthetic base stock is typically required to meet industry and OEM specifications and therefore is available only as a synthetic motor oil.

The benefits of using the correct 0W grade motor oil for your vehicle are faster flow at start-up to reach critical engine parts, faster engine warm up and delivers better fuel economy as compared to higher viscosity grade oils.
 
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This is from the pennzoil website. Mobil1 web site is similar.

0W motor oil was developed to operate in today’s modern vehicle engines, which are smaller and run hotter than older engines. In order to make a 0W motor oil, synthetic base stock is typically required to meet industry and OEM specifications and therefore is available only as a synthetic motor oil.

The benefits of using the correct 0W grade motor oil for your vehicle are faster flow at start-up to reach critical engine parts, faster engine warm up and delivers better fuel economy as compared to higher viscosity grade oils.
Not everything you read on the Internet is correct, is it? Just like their reference to “flow” which is nearly irrelevant.
 
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The other thing about a discussion over a winter rating is that it’s completely dependent on temperature and the specific oil under consideration. If the temperature is above -30 or so there’s zero guarantee an oil with a 0W rating will be thinner than one with a 5W rating. It may well be thicker. The winter rating isn’t really about fuel economy it’s about cranking and pumpability at low temperatures. Once started the oil spends relatively little time at that temperature and has minimal effect on fuel economy.
 
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Not everything you read on the Internet is correct, is it? Just like their reference to “flow” which is nearly irrelevant.
From Motul.

Viscosity grade SAE 0W-16 minimizes seriously lubricant hydrodynamic friction, allows significant fuel economy benefits especially when the oil is cold.
This very low viscosity grade also improves oil flow at start up, delivers faster oil pressure build up, faster rev raisings and allows reaching operating temperature faster.

Seems like this information is all over the net and is supported by oil and car manufacturers, not just one person’s opinion.
 
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From Motul.

Viscosity grade SAE 0W-16 minimizes seriously lubricant hydrodynamic friction, allows significant fuel economy benefits especially when the oil is cold.
This very low viscosity grade also improves oil flow at start up, delivers faster oil pressure build up, faster rev raisings and allows reaching operating temperature faster.

Seems like this information is all over the net and is supported by oil and car manufacturers, not just one person’s opinion.
I’m not the only one, I can’t take all the credit. Make sure you address what Overkill posted as well.

There’s a bit of obfuscation in those statements you’re posting. Faster “reving” will indeed heat up the oil faster due to higher shear in the bearings. But the warmup sequence on a car is dictated by the ECU, not the oil. Yes engines have higher revs on startup but that’s to force it to warm up faster.

I know you really want it to be true that a lower viscosity oil heats up faster but that’s a violation of physics so we are going to have a hard time proceeding from here.
 
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I’m not the only one, I can’t take all the credit. Make sure you address what Overkill posted as well.

There’s a bit of obfuscation in those statements you’re posting. Faster “reving” will indeed heat up the oil faster due to higher shear in the bearings. But the warmup sequence on a car is dictated by the ECU, not the oil. Yes engines have higher revs on startup but that’s to force it to warm up faster.

I know you really want it to be true that a lower viscosity oil heats up faster but that’s a violation of physics so we are going to have a hard time proceeding from here.
Can’t let it go? See, overkill wasn’t so bombastic as your posts seem to be. I’ll trust the engineers for oil and car makers. Thanks for your posts.
 

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The benefits of using the correct 0W grade motor oil for your vehicle are faster flow at start-up to reach critical engine parts, faster engine warm up and delivers better fuel economy as compared to higher viscosity grade oils.
OK, so instead of regurgitating oil company marketing, put on your critical thinking hat for a minute.

1. Oil pumps are positive displacement, which means that as long as the pump isn't on the relief, the same volume of oil is being forced through the engine. So "flow" is the same provided those caveats are observed.

2. The only place #1 fails to address is cylinder wall lubrication, which is achieved by the shearing action of the rod on the rod journal, which forces out a spray of oil that lubricates the bores. Some engines also have piston cooling jets that spray on the bottom of the pistons to aide in heat removal (my 6.4L has these). Both of these mechanisms work better with thinner oil, and since all oil thickens when it cools, the closer to "hot" viscosity the oil is, the more effective these are going to be. In application, this has very little impact on longevity however.

3. It does not lead to faster engine warm-up as we've already discussed. An engine's generation of heat is directly tied to how much fuel it consumes. Remember, engines are horribly inefficient at converting chemical energy into mechanical energy, the biggest share of that chemical energy ends up as heat energy. Ergo, the more load that's on the engine, the more fuel it is going to use, the more fuel it uses, the more heat it is going to produce and the more heat it produces the faster it is going to warm up. As I already mentioned, you also have the shearing effect of the bearings on the oil itself and heavier oil generates more friction, which in turn means more heat, as well as more drag, which means more fuel. Follow?

4. Fuel economy. Absolutely. As I already noted, the purpose of using thinner lubricants is to primarily improve fuel economy during the period where the engine is least efficient, and that's during warm-up. The closer the oil is to operating viscosity, the less drag is placed on internal parts, the easier the oil pumps, and the less fuel the engine has to use to provide the same power. While these are all small fractional gains, they do add up to a measurable impact on fuel economy.

As I already said, OEM's have been working to decrease warm-up time of both oil and coolant and they've been doing this by:
1. The fitment of electrical fans in place of mechanical fans
2. The fitment of coolant/oil heat exchangers. Coolant comes up to temperature MUCH faster than oil does (where does the majority of that aforementioned heat energy go? Right into the coolant) so these devices use the coolant to heat the oil, rapidly reducing viscosity, drag, and the impact on fuel economy.
3. The fitment of grille shutters. This is probably the most recent "tweak". Block off airflow through the radiator, which causes the coolant to come up to temperature faster. Couple that with a coolant/oil heat exchanger and you significantly decrease the time required to get both fluids up to operating temperature.


Also, keep in mind, the number in front of the SAE grade, so in this case, the 0W-xx is the WINTER rating of the lubricant. A 0w-40 is significantly heavier than a 0w-20 and a 0w-20 with a low VI can be heavier at most temperatures than a 5w-20! However, the beauty of the 0w-xx Winter rating is that it works anywhere from Texas to Alaska, which allows these oils to be "universal", which is why they've become so popular in recent years.
 
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OK, so instead of regurgitating oil company marketing, put on your critical thinking hat for a minute.

1. Oil pumps are positive displacement, which means that as long as the pump isn't on the relief, the same volume of oil is being forced through the engine. So "flow" is the same provided those caveats are observed.

2. The only place #1 fails to address is cylinder wall lubrication, which is achieved by the shearing action of the rod on the rod journal, which forces out a spray of oil that lubricates the bores. Some engines also have piston cooling jets that spray on the bottom of the pistons to aide in heat removal (my 6.4L has these). Both of these mechanisms work better with thinner oil, and since all oil thickens when it cools, the closer to "hot" viscosity the oil is, the more effective these are going to be. In application, this has very little impact on longevity however.

3. It does not lead to faster engine warm-up as we've already discussed. An engine's generation of heat is directly tied to how much fuel it consumes. Remember, engines are horribly inefficient at converting chemical energy into mechanical energy, the biggest share of that chemical energy ends up as heat energy. Ergo, the more load that's on the engine, the more fuel it is going to use, the more fuel it uses, the more heat it is going to produce and the more heat it produces the faster it is going to warm up. As I already mentioned, you also have the shearing effect of the bearings on the oil itself and heavier oil generates more friction, which in turn means more heat, as well as more drag, which means more fuel. Follow?

4. Fuel economy. Absolutely. As I already noted, the purpose of using thinner lubricants is to primarily improve fuel economy during the period where the engine is least efficient, and that's during warm-up. The closer the oil is to operating viscosity, the less drag is placed on internal parts, the easier the oil pumps, and the less fuel the engine has to use to provide the same power. While these are all small fractional gains, they do add up to a measurable impact on fuel economy.

As I already said, OEM's have been working to decrease warm-up time of both oil and coolant and they've been doing this by:
1. The fitment of electrical fans in place of mechanical fans
2. The fitment of coolant/oil heat exchangers. Coolant comes up to temperature MUCH faster than oil does (where does the majority of that aforementioned heat energy go? Right into the coolant) so these devices use the coolant to heat the oil, rapidly reducing viscosity, drag, and the impact on fuel economy.
3. The fitment of grille shutters. This is probably the most recent "tweak". Block off airflow through the radiator, which causes the coolant to come up to temperature faster. Couple that with a coolant/oil heat exchanger and you significantly decrease the time required to get both fluids up to operating temperature.


Also, keep in mind, the number in front of the SAE grade, so in this case, the 0W-xx is the WINTER rating of the lubricant. A 0w-40 is significantly heavier than a 0w-20 and a 0w-20 with a low VI can be heavier at most temperatures than a 5w-20! However, the beauty of the 0w-xx Winter rating is that it works anywhere from Texas to Alaska, which allows these oils to be "universal", which is why they've become so popular in recent years.
Good post Overkill. Hopefully you weren't too bombastic.
 
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OK, so instead of regurgitating oil company marketing, put on your critical thinking hat for a minute.

1. Oil pumps are positive displacement, which means that as long as the pump isn't on the relief, the same volume of oil is being forced through the engine. So "flow" is the same provided those caveats are observed.

2. The only place #1 fails to address is cylinder wall lubrication, which is achieved by the shearing action of the rod on the rod journal, which forces out a spray of oil that lubricates the bores. Some engines also have piston cooling jets that spray on the bottom of the pistons to aide in heat removal (my 6.4L has these). Both of these mechanisms work better with thinner oil, and since all oil thickens when it cools, the closer to "hot" viscosity the oil is, the more effective these are going to be. In application, this has very little impact on longevity however.

3. It does not lead to faster engine warm-up as we've already discussed. An engine's generation of heat is directly tied to how much fuel it consumes. Remember, engines are horribly inefficient at converting chemical energy into mechanical energy, the biggest share of that chemical energy ends up as heat energy. Ergo, the more load that's on the engine, the more fuel it is going to use, the more fuel it uses, the more heat it is going to produce and the more heat it produces the faster it is going to warm up. As I already mentioned, you also have the shearing effect of the bearings on the oil itself and heavier oil generates more friction, which in turn means more heat, as well as more drag, which means more fuel. Follow?

4. Fuel economy. Absolutely. As I already noted, the purpose of using thinner lubricants is to primarily improve fuel economy during the period where the engine is least efficient, and that's during warm-up. The closer the oil is to operating viscosity, the less drag is placed on internal parts, the easier the oil pumps, and the less fuel the engine has to use to provide the same power. While these are all small fractional gains, they do add up to a measurable impact on fuel economy.

As I already said, OEM's have been working to decrease warm-up time of both oil and coolant and they've been doing this by:
1. The fitment of electrical fans in place of mechanical fans
2. The fitment of coolant/oil heat exchangers. Coolant comes up to temperature MUCH faster than oil does (where does the majority of that aforementioned heat energy go? Right into the coolant) so these devices use the coolant to heat the oil, rapidly reducing viscosity, drag, and the impact on fuel economy.
3. The fitment of grille shutters. This is probably the most recent "tweak". Block off airflow through the radiator, which causes the coolant to come up to temperature faster. Couple that with a coolant/oil heat exchanger and you significantly decrease the time required to get both fluids up to operating temperature.


Also, keep in mind, the number in front of the SAE grade, so in this case, the 0W-xx is the WINTER rating of the lubricant. A 0w-40 is significantly heavier than a 0w-20 and a 0w-20 with a low VI can be heavier at most temperatures than a 5w-20! However, the beauty of the 0w-xx Winter rating is that it works anywhere from Texas to Alaska, which allows these oils to be "universal", which is why they've become so popular in recent years.
Very well said. Yet there still has to be something about lower viscosity oil that prompts oil and auto manufacturers to believe it’s tied to quick warm up. Also, as you point out, the engines are being designed differently (my favorite is the exhaust manifold cast as part of the head) to promote more efficient engine warm up. Can either you or Kschachn think of a reason why they give this as one of the explanation (other than fuel economy) for using lower viscosity oil?
 

OVERKILL

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Very well said. Yet there still has to be something about lower viscosity oil that prompts oil and auto manufacturers to believe it’s tied to quick warm up. Also, as you point out, the engines are being designed differently (my favorite is the exhaust manifold cast as part of the head) to promote more efficient engine warm up. Can either you or Kschachn think of a reason why they give this as one of the explanation (other than fuel economy) for using lower viscosity oil?
My only thought is they might be including it in terms of the "package" that we've already gone over with manufacturers seeking to reduce warm-up time. So, while thinner oil itself doesn't directly contribute to faster warm-up (and in fact would work against it slightly), its use, to reduce friction and power loss, while at the same time using these other mechanisms to heat the oil and expedite the warming of the coolant as a means of improving the overall efficiency of the package "fits".
 
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My only thought is they might be including it in terms of the "package" that we've already gone over with manufacturers seeking to reduce warm-up time. So, while thinner oil itself doesn't directly contribute to faster warm-up (and in fact would work against it slightly), its use, to reduce friction and power loss, while at the same time using these other mechanisms to heat the oil and expedite the warming of the coolant as a means of improving the overall efficiency of the package "fits".
Thanks for that thoughtful response.
 
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