5w-30

[OldmanTaco]

some people may want to think Toyota is always Toyota, well their Tundra engine is a turd and there seems to be problems with even the recalled and replaced engine. So I trust Toyota, but I don't trust the team trying to design something for CAFE standards in the US where most people do sever service driving, use the cheapest oil they can find and lastly blast way past the far too long oil change interval. GM has recalled 600,000 trucks changing the oil fill cap from 20 weight to 40 weight.

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[DENNISD]

some people may want to think Toyota is always Toyota, well their Tundra engine is a turd and there seems to be problems with even the recalled and replaced engine. So I trust Toyota, but I don't trust the team trying to design something for CAFE standards in the US where most people do sever service driving, use the cheapest oil they can find and lastly blast way past the far too long oil change interval. GM has recalled 600,000 trucks changing the oil fill cap from 20 weight to 40 weight.

Toyota didn’t just guess on oil weight to hit CAFE numbers. That viscosity is tied to engine tolerances, oil flow, and long-term durability testing.


If 0W-20 (or whatever spec) was actually causing widespread wear, they’d be eating massive warranty costs—and they’re not in the business of doing that.


The GM example proves the opposite of your point. They found an issue and changed the spec themselves. That’s exactly how it’s supposed to work.


Once you go outside manufacturer specs, you’re just guessing. Too many variables to claim a thicker oil is “better” without controlled testing.


I’ll stick with what the engineers who built the engine recommend.

 

[GSPHerder]

That’s because you’re looking at a cold engine. Need to compare hot to hot. Trust me, I’m running a thicker oil than you and my pressure starts where yours does cold and then it’s much lower when warm, unless revving 2000 rpm or more.

Ha, you were correct sir. Settled back down to original pressures after some miles.

 

[BLtheP]

Toyota didn’t just guess on oil weight to hit CAFE numbers. That viscosity is tied to engine tolerances, oil flow, and long-term durability testing.


If 0W-20 (or whatever spec) was actually causing widespread wear, they’d be eating massive warranty costs—and they’re not in the business of doing that.


The GM example proves the opposite of your point. They found an issue and changed the spec themselves. That’s exactly how it’s supposed to work.


Once you go outside manufacturer specs, you’re just guessing. Too many variables to claim a thicker oil is “better” without controlled testing.


I’ll stick with what the engineers who built the engine recommend.

If you woke up in Mexico tomorrow and your owner’s manual gave you a choice of 0W-20, 5W-20, 5W-30, or 10W-30, which would you choose? Which one would the engineers recommend you use?

 

[DENNISD]

If you woke up in Mexico tomorrow and your owner’s manual gave you a choice of 0W-20, 5W-20, 5W-30, or 10W-30, which would you choose? Which one would the engineers recommend you use?

If I were planning to drive my Tacoma in Mexico for an extended period, I’d follow the owner’s manual for that region—which, per Toyota Mexico, would recommend 5W-30.


This really isn’t complicated. It comes down to reading and following the manufacturer’s guidance for the conditions you’re in. Doing otherwise just opens the door to unnecessary risk, especially when it comes to warranty coverage.

 

[EatMyTaco]

If I were planning to drive my Tacoma in Mexico for an extended period, I’d follow the owner’s manual for that region—which, per Toyota Mexico, would recommend 5W-30.


This really isn’t complicated. It comes down to reading and following the manufacturer’s guidance for the conditions you’re in. Doing otherwise just opens the door to unnecessary risk, especially when it comes to warranty coverage.

Do you not see the logic behind what you just responded to?

The motor doesn't magically change because you crossed a border. If 5w-30 is mechanically ok in Mexico, it must also be mechanically ok in the USA, at least in the hot states like TX, NM, AZ, etc.

If you're talking warranty, then sure, that makes sense. But the mechanics of your motor didn't change when you crossed the border.

I'm only running 0w-20 because that's what the manual says, so I don't have a warranty issue. Once the warranty period is over, I'm going to 5w-30.

 

[DENNISD]

Do you not see the logic behind what you just responded to?

The motor doesn't magically change because you crossed a border. If 5w-30 is mechanically ok in Mexico, it must also be mechanically ok in the USA, at least in the hot states like TX, NM, AZ, etc.

If you're talking warranty, then sure, that makes sense. But the mechanics of your motor didn't change when you crossed the border.

I'm only running 0w-20 because that's what the manual says, so I don't have a warranty issue. Once the warranty period is over, I'm going to 5w-30.

My logic is pretty simple.


If you’re operating in consistently warmer climates or doing frequent hauling/towing, Toyota allows for a heavier oil in certain regions. Mexico doesn’t deal with the same cold-start conditions we do in many parts of the U.S., so a thicker viscosity makes sense there. In the U.S., oil recommendations have to account for a much wider range of temperatures, especially colder environments.


Where this discussion goes off track is when people start assuming they know better than the engineers who designed and tested the engine. Toyota didn’t pick oil specs randomly—they’re based on extensive testing across a wide range of conditions.


Could a thicker oil “work”? Probably. But that’s not really the point.


The real issue is risk. Once you deviate from the manufacturer’s recommendation—especially during the warranty period—you open the door to potential problems with coverage. For me, that alone makes it not worth overthinking.

 

[EatMyTaco]

My logic is pretty simple.


If you’re operating in consistently warmer climates or doing frequent hauling/towing, Toyota allows for a heavier oil in certain regions. Mexico doesn’t deal with the same cold-start conditions we do in many parts of the U.S., so a thicker viscosity makes sense there. In the U.S., oil recommendations have to account for a much wider range of temperatures, especially colder environments.


Where this discussion goes off track is when people start assuming they know better than the engineers who designed and tested the engine. Toyota didn’t pick oil specs randomly—they’re based on extensive testing across a wide range of conditions.


Could a thicker oil “work”? Probably. But that’s not really the point.


The real issue is risk. Once you deviate from the manufacturer’s recommendation—especially during the warranty period—you open the door to potential problems with coverage. For me, that alone makes it not worth overthinking.

You did notice that I specifically called out "hotter states," right, even by name, for the very reason you mentioned.

That being said, IMHO, I believe, IMHO IMHO IMHO IMHO that Toyota spec'd 0w-20 for efficiency over wear protection. Yes, in cold places I can see 0w-20 being a better option because of the cold-flow issue. I don't disagree with that. I also agree that most americans car owners are not gear-heads like us who self-select to participate in online discussions that may border on pedantic, like this one...and manuals are written with that in mind. Can you imagine an average american getting a chart of temp ranges for oils and having them get all confused?

I just wish they did though, so I could run 5w-30 when it's 110F outside and 0w-20 when it's below freezing without worrying about my warranty. I'd get the benefits of both and reduce wear overall. If I wasn't in one of the hot-as-ballz states, I wouldn't worry about it so much, but not being able to run 5w-30 in a place that is regularly over 90deg is frustrating when I know for a fact that "cold flow" isn't something I need most of the time.

 

[GSPHerder]

Everyone gets to pick their own poison, DennisD has subscribed to this thread so hopefully he will post some 0w-20 oil analysis so we can compare and analyze what's working and not. The last 0w-20 analysis I saw was at 20k miles and was showing increased or more than average wear.

 

[DENNISD]

Everyone gets to pick their own poison, DennisD has subscribed to this thread so hopefully he will post some 0w-20 oil analysis so we can compare and analyze what's working and not. The last 0w-20 analysis I saw was at 20k miles and was showing increased or more than average wear.

You’re looking at a very small, uncontrolled sample and drawing conclusions from it—at best, it’s guesswork.


There are far too many variables in a single oil analysis (driving habits, load, environment, maintenance intervals, etc.) to isolate viscosity as the cause.


Meanwhile, the manufacturer has already done extensive controlled testing under a wide range of conditions. That’s what their recommendation is based on—not one or two reports on a forum.


On top of that, deviating from the specified oil opens the door to potential warranty issues. You’re taking on risk based on assumptions rather than engineering data.


Everyone can make their own choice, but I’ll stick with what the engineers designed and validated.

 

[GSPHerder]

I suspected that would be your reply, makes you wonder why you post on this thread if you have nothing to contribute.

 

[DENNISD]

I suspected that would be your reply, makes you wonder why you post on this thread if you have nothing to contribute.

I am contributing—just not in the way you prefer. I’m pointing out that this is a slippery slope based on limited, uncontrolled data, and people should be aware of the potential risks involved.

 

[maxx075]

I mean unless someone is physically holding a gun to your head saying "I wouldn't use that 5W-30 if I were you. Might be the last thing you do." Use what you want. If your engine shits the bed, well you may pay attention next time, otherwise it's all good.

This thread is just a circle jerk at this point.

 

[BLtheP]

I am contributing—just not in the way you prefer. I’m pointing out that this is a slippery slope based on limited, uncontrolled data, and people should be aware of the potential risks involved.

You're not really contributing. Everything so far from you has been:

• don't question the engineers
• use whatever the manual says
• warranty concerns, warranty concerns, warranty concerns
• if you're going to make a change, prove its benefit....yet when someone proves a measured downside of 0W-20 (excessive wear on an analysis), that gets chalked up to being inconclusive because of too many variables. OK - so if I did two oil analyses, one on 0W-20, and one on 5W-30 or 5W-40 and clearly proved less wear, would that be good enough? Or still too many variables and I should still just do what the manual says? Do you see the problem with the arguments here?

We have gone full circle here - exactly what useful contributions is anyone supposed to draw from any of these points?

 

[BLtheP]

Do you not see the logic behind what you just responded to?

The motor doesn't magically change because you crossed a border. If 5w-30 is mechanically ok in Mexico, it must also be mechanically ok in the USA, at least in the hot states like TX, NM, AZ, etc.

I was going to address this but decided I didn't have the energy. But agreed, the engine does not know what side of the border it's on, and plenty of US states have same or similar climates as Mexico. You don't have to cross the border for 5W-30 to suddenly become safe.

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