In Hyundai Theta II forums it is belief that the rod bearings are made from a softer material thus suggestions for greater film strength using a 30 weight synthetic oil were recommended . I was hoping by 2017 most Theta II failures would be gone but the failures continued through the life of the Theta II with rod bearings and other Theta II design shortcomings continuing leading to engine failure. My Theta II 2.4L at 60K miles sees 3,700 mile / 6 month OCI’s using mostly M1 5W30 oil with regular oil level checks. So far , the engine lives on but that may be more to do with luck than my oil and shorter OCI choices (although my oil and OCI can’t hurt !)
2021 Odyssey oil spec
- Thread starter MrStamper
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Patman
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This is exactly what got me thinking about all of this thin oil nonsense. My Toyota Camry has the same, "recommendations". Except it shows all the way up to 15W-40 is OK to use in the foreign country manuals. Where CAFE doesn't exist. They also claim right in the US manual, "A thicker viscosity may be a better choice if the vehicle is operated in severe conditions".
Then there is the nonsense that says...."If 0W-16 is not available, you can use 0W-20. Just as long as you change back to 0W-16 the next oil change". What a bunch of malarkey. An oil, regardless of viscosity, is either OK to use. Or else it isn't.
Can you run 0W-16? Sure.... But why would you?
If other countries allow one grade higher viscosity in the same engine as US, there is zero issues if you use higher viscosity. Corvette owner manual clearly shows that they want you to use higher viscosity when car is tracked. Some people keep repeating that thicker oil cools less, it is true, but the difference in cooling between 20 and 30 grade is negligible and does not matter. Tolerances are the same as they were 20 years ago. Oil changes viscosity as it heats up and cools off, so by definition engines have to be able to work with the range of viscosities.
I've run 5W30 in everything that's called for a 20 weight. I might have run a 20 weight once in one of my vans in the last 10 years.
North American car manuals are CAFE written, when it comes to oil recommendations. I remember the Subaru having the same single viscosity in my manual, while overseas manuals had a chart showing all the way up to 20w50.
North American car manuals are CAFE written, when it comes to oil recommendations. I remember the Subaru having the same single viscosity in my manual, while overseas manuals had a chart showing all the way up to 20w50.
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Your Hemi and 3.6 spec 0w20 for every country on the planet earth. I am not sure about Mars, you could experiment with another viscosity there.
The 5.7 HEMI used 5w-30 in the HD trucks.
Grades aren’t a “spec” they are a recommendation.
OVERKILL
$100 Site Donor 2021
Bearings are "self pumping", they generate their own oil wedge and draw from the galleries where the oil pump is providing a "head" of oil. Thinner oil flows through the bearing quicker, so the draw-down rate on the galleries is increased, couple this with increased leakage from all of the fixed orifices, and of course this is why you observe lower oil pressure. However, high pressure at the bearing galleries is not required, this is why engines without oil pumps can still function. Back in the day we even had engines that were gravity oiled.
I wouldn't call it "mist", it's the spray off the rod bearings.
Viscosity is directly related to temperature, which can change the realm in which lubrication is taking place in the engine. If you are familiar with the Stribeck curve:
We have parts operating in all three realms and some, like pistons and rings, that move between them, going from hydrodynamic to mixed to boundary and back again, depending on where they are in the bore and what stroke they are on. This is why the anti-scuff coating on piston skirts wears off over time. Increasing viscosity can shift where in the Stribeck curve a component is operating, for a given oil temperature, as it increases the MOFT.
Hydrodynamic is zero wear, this is where bearings are supposed to always operate. The Japanese OEM's, focused on fuel economy, fitting wider bearings, to allow them to tolerate some of the super thin oil grades we are now seeing, as a wider bearing can sustain an adequate MOFT with a thinner lubricant, while maintaining the same load carrying capacity. They found friction reduction in the mixed/boundary realm in certain parts of the engine, enhanced by various FM's and coatings, this improved fuel economy, which is what drove the pursuit of tinner lubricants.
My understanding of the GM issue, at least in part, is that due to manufacturing issues with the crankshaft, some of these engines are having bearings operating outside of the hydrodynamic realm with the spec 0W-20, which leads to wear, and eventually failure. The heavier lubricant provides a greater MOFT, which may postpone the manifestation of this issue.
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In theory, but that's why you have a cooling system. In practice the oil will not be any hotter unless your cooling is insufficient.
Jk I’m
and how much cooler 20 vs 30 grade, is it like 1-2C? Does it matter?
The hotter the oil the better it cools. Same goes for the coolant temperature.
Oil pressure is not a substitute for viscosity.
Flame suit on.
I crossed that bridge a while ago, driving Hondas with the 1.5t engines that, unless operated under optimum conditions, tend to dilute oil, sometimes more sometimes less. 0w20 oil, combined with Hondas MM is not a good choice for engine longevity as numerous UOA's have demonstrated. With the approval and reccomendations from my dealership, my Honda Certified Master Technician and others here on the forum, I switched to Mobil1 5W-30 EP, Technician indicating now minimal rise on the dipstick and virtually no gas smell when changing using 4-5k intervals in my 2023 Civic Touring Sedan. No mpg drop evident with actual calculated figures. My wife's HRV with the 2.0NA engine will use 0w20 without drama and will get shorter OCI'S due to it's usage as a grocery getter with only occasional highway miles. All this with the knowledge that many Hondas survive despite their following the MM and usage of dealers bulk oil. My Technician has also told me some of the horror stories of some Hondas with minimal maintenance and heavy oil dilution. BTY, our CVTs get a spill-n-fill every 30k. IMHO pro-active maintenance is far better than reactive maintenance if you want fewer problems in the long run.
I've run 0W-20, 5W-30 and 0W-40 in a 5.7 HEMI in all four seasons and the temperature difference is zero.
Many engines now have direct oil flow to pistons. There are piston squirters aiming oil at the piston underside and at BDC these squirters will often directly inject oil into a hollow cooling gallery within the piston. These engines will give oil flow in the con rod taking pressure off the rod bearing to directly supply the wrist pin and pin joint.
Mist is a surprisingly effective means of lubrication. Many large industrial plants like refineries have electric motors lubricated by a steady supply of oil mist fed through a centralized misting distribution system. These motors can last many, many hours— 150k hours isn’t unheard of. My understanding is that mist can sometimes lubricate *better* than full flow liquid and the mist not only lubricates wel, it drastically reduces windage and viscous pumping losses that would drag on the motors.
I don’t know that thicker oil necessarily means “less lubrication” but it certainly means more parasitic losses.
The GM L84 6.2L engine and the LT4 have IROX-coated main bearings, but not rod bearings. Other manufacturers, like Stellantis, use IROX-coated rod bearings in the 3.6L PUG engine. This effectively enables the implementation of Start/Stop "technology" and supports heavier engine loads while running on fuel-economy oils like 0W-20. In hindsight, GM should have followed the lead of Japanese manufacturers and made the rod bearings wider—but then again, there’s only so much room on the crankshaft in a V8 engine.
The lack of transparency has given rise to speculation, ranging from mild to wild.
In my personal opinion, there’s nothing inherently wrong with thin oils, as long as everything is perfectly within spec. And what I mean by that is this: the engine design is sound, the manufacturing is done within specifications, the materials meet or exceed those specifications, and everything inside the engine is functioning properly—no leaky injectors, no fuel dilution, etc.
However, the reality is that, especially in today’s economic conditions and the ever-increasing pursuit of profit, nothing is perfect. I prefer to be cautious and leave myself some margin for error, so in all of my vehicles, I stick with engine oils that have an HTHS rating above ~3.2, preferably around 3.5. Of course, if I move toward 4.0, I start to see a dip in fuel efficiency, which isn’t ideal.
My speculation about GM is that the bearings are not up to spec. However, a higher HTHS oil can mitigate the issue. It could be related to the IROX coating on the mains—though I haven’t seen IROX-coated bearings fail—but more likely, it’s the rod bearings being “cheaper than they should be.” That would be consistent with GM’s tradition of cutting corners and saving a buck where they could have saved just a quarter.
The lack of transparency has given rise to speculation, ranging from mild to wild.
In my personal opinion, there’s nothing inherently wrong with thin oils, as long as everything is perfectly within spec. And what I mean by that is this: the engine design is sound, the manufacturing is done within specifications, the materials meet or exceed those specifications, and everything inside the engine is functioning properly—no leaky injectors, no fuel dilution, etc.
However, the reality is that, especially in today’s economic conditions and the ever-increasing pursuit of profit, nothing is perfect. I prefer to be cautious and leave myself some margin for error, so in all of my vehicles, I stick with engine oils that have an HTHS rating above ~3.2, preferably around 3.5. Of course, if I move toward 4.0, I start to see a dip in fuel efficiency, which isn’t ideal.
My speculation about GM is that the bearings are not up to spec. However, a higher HTHS oil can mitigate the issue. It could be related to the IROX coating on the mains—though I haven’t seen IROX-coated bearings fail—but more likely, it’s the rod bearings being “cheaper than they should be.” That would be consistent with GM’s tradition of cutting corners and saving a buck where they could have saved just a quarter.
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My truck is modified a little, it never hits 100C half the year unless it's idling. Summer and towing it gets a little hotter, but towing on the straights with 5w-30 it is still colder than stock unloaded with 5w-20.
I have exactly 0 worries about any theoretical temp difference in oil.
edyvw
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Is thermostat or water pump electronically controlled? BMW’s go colder when tracking, pushing, towing than when coasting on HWY. DME has 4 predetermined operations for electric water pump or in newer models for electric thermostat.
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