Las Oil Change I used 5w-30 instead of 5w-20

Rod Knox, I can’t speak to what Lexus or Willys did, but if it’s possible to spec a single grade of oil for all operating conditions then it’s a good thing to do to reduce customer confusion. And there’ve been a lot of changes in oil chemistry and engine design practices in the last 60 years.

Docnick, yes, fuel economy regs are one of the things that drive viscosity, but they aren’t the only thing. Sure, a manufacturer might recommend different viscosities in different climates, but before they do they validate the engines that way. The fact that some vehicle have multiple oils spec’d doesn’t mean that it’s a good idea for the owner of a different vehicle to use an off-spec oil. Also, if you live in a severely cold climate and thought that you’d increase the sub-zero cold start viscosity by going from 0W-20 to 0W-30, you may well have actually ended up doing the exact opposite of your intent.

the same mountainbike, yes, in a nutshell that’s how the friction modifiers work, but their effect on high-temperature-high-shear viscosity (which dominates in the hydrodynamic bearing gap) is different than their effect on the low-temperature-low-shear viscosity (which dominates in most other places). It’s one of the dozens of engineering tradeoffs that need to be comprehended in the design of the engine.

I think Chilehed made a typo on the oil thickness and I agree with hin a 100% on using what the manus say,( you can put about anything in a wheezy oil burning wore out clunker-oil wise that is, matter of fact I think my boss ruined his wifes honda by insisting on runniing 10w-40 in it-Kevin

@chilehed Going from 0W20 to 0W30 is not to lower the pour point or "borderline pumping ", it is to ensure that we have good film strength at high speed and higher opertiong loads and temperatures.

Looking through the lubricant’s handbook of a popular major oil company, I find for their synthetic oils, the borderline pumping virtually the same for the 0W20 and 0W30. The 0W30 has a slightly higher Viscosity Index at 172, vs 169 for the 0W30. This same company’s regular mineral oils have a Viscosity Index of 155 for the 5W20 and 159 for the 5W30.

I agree that more engines are destroyed in the US through racing a very cold engine than by driving fast across the Mohave desert in the summer. Most of Europe is a lot milder than the US, and fast driving dictates heavier oils like 0W40 synthetic.

The 0W30 synthetic cover a wide range of operating conditions resulting in maximum engine life. I have been using this type oil for a long time and have never disposed of a car because the engine was worn out. We keep our cars 15 to 20 years.

A friend tows a heavy trailer to Florida each year from the cold North. He uses 15W40 mineral oil in his F-150 and uses an engine block heater for safe and easy starts in the North. He could use a 5W40 synthetic as well, but does not want to spend the money.

A layman’s oil viscosity explanation.

When I read chilehed’s initial post in this thread (Jan 2nd), it felt like a breadth of fresh air.
While I don’t have his expertise in engine lubrication, I have been on many design teams over the years, and his input struck a familiar tune.

What I took away from chilehed’s comment was there are many factors and constraints that go into how an engine design and oil spec work together. (EPA mileage is only one of them). Whatever ends up being spec’d is what ends up getting tested through the verification and test cycles.

When someone decides to use a lubricant outside of what’s been spec’d, they’re really on their own. The fact that many other car owners did it on previous years’ models may mean it will work, but you’re still on your own.

The 5w30 that the OP accidentally used may be totally fine. Or it may be right up against some flow tolerance for the variable valve mechanism. The point is we don’t know, and it either was tested during design and not chosen for a reason, or it wasn’t tested because it was beyond spec.

It appears that there is a strong bias toward lighter viscosity oils, as though thinner is always better. I might guess that such a bias is the rebound from the popularity of heavier oils, especially 20W50 “racing” oil, that became so popular 30+/- years ago. If, in an effort to avoid confusion for easily confused consumers, the automobile manufacturers nail down a single grade and hang their reputation on it it would be logical that they single out the grade that is best suited for the climate where they live and work and in the US that would be the Great Lakes area. And, in fact, would GM, Ford, MoPar ever consider the climate of Needles California when the market there is so insignificant? Hardly. But as the link indicated, Lexus apparently considered the climate of Singapore when they recommended 5W40 oil for that market. It is quite unlikely that one grade is perfect for all climates and conditions. And the greatest problem with the “state of the art” oils of today is the inherent tendency to sludge that worsens as the spread between the low temperature and high temperature rating spreads. But Lexus engineers felt it worthwhile to push their luck at risking sludge to counter the effects of the warm climate in Singapore with 5W40. But I am so often amazed at the contradictions and inconsistencies issued from the corporate committees. They removed the drains from GM radiators and installed 4 cylinder transmissions on V-8s and built engines that shut off fuel to cylinders to improve fuel economy and wondered why the Japanese were taking over the market.

My Honda owners manual says that I can use 5w-30 1 time but make sure to return to 5w-20 next oil change. I’ll bet yours does, too. In any case, it won’t hurt your engine.

@Conoso–The manual for our 2003 Toyota 4Runner specifies 5W-30, but says that 10W-30 could be substituted if the oil is replaced with 5W-30 at the next oil change. I did have a Toyota dealer put in 10W-30 instead of the prefered viscosity. It was summetime, so I just let it go. However, I never took it back to that dealer for an oil change. That particular dealer also handled GM makes–Buick and Pontiac. My guess is that the GM cars at that time specified 10W-30, so that was the oil that went into everything.

I must weigh in on this discussion too. As a Design Engineer, I am in agreeance with Chilehed. This is not a matter of what we all THINK. Degreed Engineers specifically designated a grade of oil to the engine. You could fill the oil reservoir with desil fuel and the engine would run, for a while. The point is, you are playing with fire, (i.e. your warranty) & if you change what is specified, failure or odd sounds are your fault. From the seals ability to function with the designated grade of oil, to your engine’s ability maintain proper oil pressures, off weights will result in variabilities all around. Why go against the engineers who designed it? Are you now going to re-stitch your parachute because you think the people who designed it were wrong? Then jump from 15,000 feet to test your first stitch job?

People that designed the oil weight are not wrong…but it is also ok to use similar and alternative weights of oils.

Common sense will work fine here. You don’t need an engineering degree. Most people are not autobahn folks, and most people have common sense.

Ford Mustangs recommend 5w20 in a 2000 Mustang 3.8L engine. I am satisfied with 150K miles on it and it is still running strong…using 5w30. Common sense prevails, my pocket book prevails as at the time 20weight cost a lot more.

I don’t think I need to use the prescribed oil if my cheaper dino 30 weight gets me to cross the 250K mile odo mark. good enuf for me.


Do you realize that you revived a 5 month old thread?

Even in the face of technical experts I will insist that the perfect oil for any given car driven in Detroit in the month of January is not the perfect oil for that same car driven in Barstow, California in July. Looking into factory recommendations always uncovers a chart of oil viscosity/local temperature charts that range from the thinnest to the thickest oils relative to temperature.

It seems reasonable to believe that a 5W-30 oil’s viscosity when warmed will have the viscosity of a 5W-20 oil at some point during the 5W-20 oil warmup process. Gentle throttle applications when an engine is cold might be more important with 5W-30 oil when 5W-20 is specified but after engine warmup, I would not be concerned with the use of 5W-30. Releasing such a directive in an owner’s manual will not work with everyone.

It’s interesting to note that GM specifies 5W-30 for their 2L turbocharged four and their non-turbo 3.6L V-6 but 5W-20 for their non-turbo 2.5L four . The owner’s manual specifically forbids the use of 10W-30, 10W-40 and 20W-50 for all three of these engines but does not forbid the use of 5W-30. 0W-30 is permitted when the temperature falls below -20F.

Engineers must summarize and simplify instructions intended for use by the general public and can not go into exceptional detail or some consumers will end up being confused, will ignore the instructions or will even not read the owner’s manual.

Hopefully the OP has changed the oil by now so its a moot point.

As I said, this thread is pretty old . . .

I don’t why someone flagged me “off topic”

That is just plain cold

Someone resurrected a very old thread.

I merely pointed that out.

Apparently, someone wants to keep discussing 5w30 versus 5w20 . . .

Just remember OP is almost certainly not reading this anymore.

And hasn’t been for months now . . .

Using weights as 0 or 5 represent startup preferences wile motor is cold
A warmed up motor at Operating Temp will run best with a 20 or 30 depending on
factory recommendations
So yes your car could sound ticker like a sewing machine on a 5w30 Motors are built to close spec’s & require what is recommend Yet no need concern of the winter weight of 5 or 0
If the Honda had 300,000 miles using a 5w30 over a 5w20 would be compensated due to wear and extra clearance (but not always ) some motors stay very new even at high mileage
But a motor at 10,000 is very new go back to the 5w20 weight soon

This thread started in 2013 so the advice is a little late.


I still suspect that the software “feature” (I use the term loosely) that pops up the block that says “your question is similar to” and list old threads of all ages is the primary suspect in the exhumation of all the very old threads popping up. It’s essentially encouraging the poster to open the old threads, and even making it easy for them to do so.

Cyberfolks, I recommend that you reconsider the wisdom of this “feature”.


All-in-all, this seems like a case of poor reading comprehension.
In addition to that advice not being timely in regard to a thread that is now 5 years old, the OP clearly stated that the engine had 110,000 miles on it, not 10,000 miles.

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