0w-8 vs 0w-30
- Thread starter Wiremanjon
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0w-8 is preferred/recomended as shown in the image but still allow the use and recommend thicker instead for high speed driving which is everyone.
The variable oil pressure is part of the overall strategy to reduce horsepower requirements, not to accommodate low viscosity oils. VVT reduces fuel consumption for the same reason.
None of that accommodates or allows the use of low viscosity oils. Even if it did it wouldn’t preclude the use of a higher viscosity. That’s not how it works.
Yeah I was just being silly in regards to the grossly incorrect information that’s out there on certain websites and YouTube videos from people that claim to be knowledgeable.
I think there's a concern that the heavier grade will, by function of its viscosity, increase the oil pressure read by the DME and result in a scenario where there's insufficient flow. Say on 0w8 the system tries to maintain 20 psi at 1k rpm but a 0w30 reading 20 psi at 1k rpm is pumping at X psi < 20.
Whats a DME?
How would viscosity change the pressure reading? How does it read pressure when it starts at -30F and the viscosity is like 100?
Flow is not a concern. Even if it were, then under the situation you're proposing above the engine would be essentially starved every time the oil is cooler than normal operating temperature. Up here in the great north I guarantee you that many vehicles do not reach normal operating temperature on many short(ish) trips. They all must be on the verge of failure due to insufficient flow.
DME = vehicle computer. The computer controls the amount of flow based on various maps that use rpm and PSI to determine volume pumped.
Pressure is measured as resistance to flow right? People always comment how they use heavier oil to increase the oil pressure read on their gauge. Right? During start up the pump maybe in relief but I'm talking about during the warm up phase and at operating temp.
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IMO, this is strictly for EPA/CAFE compliance. Toyota isn't the only automaker that says this either.
Just wait, maybe not here, but some will argue they use different engines.
Key word being "recommend".
OK, DME = ECM ?
But according to the manual, it modulates to a pressure. So the variable pump is modulated until the desired pressure is achieved, not the other way around. So in your example where setpoint is 20PSI, the ECM (DME?) will adjust the discharge volume of the pump until 20PSI on the pressure sensor is achieved. The 20PSi (138kPa) is the primary control variable and the pump volume is increased or decreased to achieve it.
I would think one should work up only one grade at a time. See what viscosity one's engine seems to "Like." So, one would first try a 0w-16, then 0w-20, etc. Regardless your engine has not been harmed by running the oem spec oil. Relax and have a good weekend. .02
like every other variable displacement pump. difference is there's more set points than most others
It is a little misleading but it’s required for CAFE. The oil that was used for testing must be recommended to users. Manufacturers cannot test with a 0w-8 and then recommend a 5w-30 in the manual.
The “you can use other viscosities part…” is a clue most people don’t really think through logically. If Toyota says you can do it then clearly it will not cause any harm. Like when they say you can use fuel with up to 15% ethanol but no more. They don’t say “well you can use 20% ethanol this time, but next time…” It’s 15%, and no more, that’s the stopping point.
If thicker oils had any negative impacts other than fuel economy they would full stop you at the point of potentially causing harm.
Correct and the concern is that there's insufficient flow because the PSI is comparatively higher by virtue of using a heavier oil.
I have a 2025 Toyota Rav4 with the A25A-FKS engine. I have been through this on Bitog a few months ago. Ultimately, it varies from dealer to dealer I think, however, according to the Service Manager here I can use up to a 5W-30 year-round if I want to. Using the 5W-30 will not cause a warranty issue if there would be an engine failure. Don't exceed 5000 mile or 6-month oil change intervals, especially if there is quite a bit of city driving involved. Notice the wording, they "recommend" 0W-8 or 0W-16. Recommend and require are two different words, and meanings. In my owner's manual I can use from a 0W-16 to a 5W-30. I have been running 0W-30 or 5W-30 for a few months now. I have had no issues; I can't see a noticeable loss in fuel milage though I am sure on a test stand in a controlled environment there would have to be.
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If that is the case, it would make sense for the car to ask what viscosity oil is being run. Then it could run a different psi/flow program.
In their controlled environment, for CAFE compliance, they are measuring MPG down to tenths of miles or something, then this increase is multiplied across their entire FLEET. So yeap, we aren't likely to ever see any difference, but they do.
It doesn’t matter. When you hit the gas pedal and create load on the oiling system will adjust to compensate. Our Toyota is a hybrid which is constantly stoping and starting and while under load. If it was incapable of maintaining oil volume and pressure it would have been damaged by now. For reference I’ve been using 0w-20 since we bought it at 15K miles and now it’s at 52K miles.
This is a solid engine design that has been out since 2018 with very few issues and it has been put into a lot of Toyota’s line up. I don’t know where people are getting this idea that it’s so hyper sensitive.
A used oil analysis will not show you much, if this is a short-term vehicle for whatever years less than 10, use whatever. If you want to keep this vehicle for longer than 10 years, go with Valvoline Restore and Protect. I would suggest 5W-30!
Just my two cents... I'll bet it's fine running the 0w-8 with appropriate intervals. Climate is something I would consider. If it's short-tripped in arctic winters... then I'd prefer the 0w-8. If it's in stop and go traffic in Phoenix summers then I'd run a 30 grade (I wouldn't stress about the Winter rating at that point) personally.