BUT it seems that my car (2008 Lexus ES 350) that was originally recommended to use 5W-30 was reevaluated by Toyota and can now use 5W-30; 0W-30 or 0W-20. Being in Northern Colorado in winter I’d prefer the 0W oil. So here are my questions
Why would a manufacturer change their recommendations on oil.
Would 0W-30 be the best for winter driving with a commute of over an hour one-way (through Denver)
Would I even consider doing something like 0W-20 in winter and 5W-30 in summer?
Did they provide temperature range where it shows what oil to use in what conditions? Or just say you can use any of the 3? That’s pretty important.
Without additional info, 5W is pretty thin so I don’t think it’s critical, but for the winter if you want to switch to 0W I don’t think it will cause any harm, especially the 0W-30, I don’t know I would go with the 0W20 without an additional reason.
The “xW” is not the running (warm) viscosity of the oil, the -20 or -30 is.
5W-30 means it’s a multigrade oil that is 30 weight at operating temperature and has a cold viscosity equal to that of a 5 weight oil at low temperatures. It doesn’t mean that the oil is the viscosity of 5 weight oil at operating temperature when it’s cold.
Car manufacturers are finding that modern, lighter oils protect just as well as heavier ones, and have a measurable impact on fuel economy.
If they are recommending 20 weight oil, use it year-round. The only reason to use a heavier oil would be on an old engine with bad clearances that burns oil. A heavier grade will reduce oil consumption.
Any of the three and I know people in hotter climates prefer 0W-30. I like the idea of using 0W-20 but I’m worried about the lower weight in stop and go commuter traffic.
How many miles are on this car? Not that is really matters, but if it is a higher mileage car I would stick with the oil you are using. I see no advantage to changing oil weights.
Other than at initial start up, and only for a few minutes, the first number means little. Most of the time, almost all of the time, your oil weight for operating temperature is the second number. The W means Winter, that is the viscosity of the oil only when it is cold. The rest of the time it is operating at the second viscosity.
0W-20 in Winter means that you are running 20 weight viscosity oil in winter. So you would be moving to a thinner oil from 5W-30. There is no advantage or really any difference gained by switching to 0W-30 since the car will be operating at the same weight/viscosity of oil as the 5W-30 you have been using.
They’re finding that lighter oils protect as much when they design the engine for the lighter oils, to at least some degree. My understanding is that the design and engineering of bearing tolerances assumes a certain oil film thickness. Presumably a mismatch there would lead to reduced protection, with the worst case scenario being a motor designed for a relatively high viscosity, thick oil film sun edgy running on a lower viscosity thin oil film.
If you lived in Yellowknife NT or Barrow Utqiagvik AK, it would be appropriate to run the lowest weight possible for ease of start-up.
Considering a range from, say, San Diego to Utqiagvik, how cold really is it in winter where the OP lives?
My bet is it’s plenty warm enough in northern Colorado in Feb to run 5W-x.
As to -20 vs -30 the car is 12 years old and you talk about a daily commute. Good bet the car’s over 100K miles and may be closing on 200K. It’s more than ready for -30 & may not be happy on -20 regardless of temperature.
I second this, I would not use the 0W-20, I see no benefit to your situation. But you might get some out of the 0W-30 on cold startup, in the winter, especially as you said it’s a bit rough.
Like others have said, the 5w or 0w is the “winter” number. It indicates that the oil acts more or less like a SAE 5 or 0 weight oil at specified temperatures, which basically means that it’s within a certain viscosity band and is pumpable at those temps.
The 20 or 30 means that at a specific reference operating temperature, the oil falls within a certain viscosity band that corresponds to SAE 20 or 30 at that temp, which is 100C/212F.
Unless you live somewhere where it’s REALLY cold (like North Dakota, Canada or Alaska), the difference between 5 and 0 is negligible.
The 20-30 is probably not that critical either; most engines also require viscosity within a band as well, and I’m guessing that your 2008 engine probably just didn’t have 20 weight oil specified when it was produced, but that identical later year models were. That’s how my truck works; the 3.7L v6 in it is rated for 5w-30 in my model year, but a few years later, they rated it for 5w-20 as well. No significant changes in the actual engine during that time though.
Here’s an article that talks about it in a lot of detail:
If it was me, I’d just use whatever’s cheapest that falls within those three categories. It’s really not worth getting very wound up about; your car’s engine will almost certainly outlast the rest of the car anyway, even if you make it to 250k miles.