Oil Viscosity, CAFE, and your Taco Engine

I've only run 5W30 in my 1GR but when I switched from 0W20 to 5W30 in our Subaru FB25 there was a reduction in fuel economy.

 

For the crowd who believes that a major automaker like Toyota isn't willing to trade long-term durability for an MPG rating, think again.

https://www.freep.com/story/money/c...ca-deal-tesla-consumers-subsidize/1338589001/

From the article:

 

What I can say here is pretty much yes. Toyota balances several things.

They need to comply with EPA regulations, DOT regulations, warranty concerns, market quality perception. If they can squeak out a couple more MPG on average using super thin oil then that satisfies the EPA. If that oil is <just> good enough that engines last 100k that satisfies warranty. They want not to be fined by the EPA while also not replacing a ton of engines. You know accountants surely are calculating the crossing point between those.

The hitch is if the majority of people keep their trucks for 20 years then they notice that engines aren't lasting or start smoking sooner than they used to then that could be a problem. They didn't start making the recommendation for 0W20 in 1GR until fairly recently. My 2008 still suggested 5W30, so I suspect data will start coming in over the next few years whether running the thin oils has been bad or not.

 

They said this years ago when the Obama administration came up with the MPG targets. That there's only so much improvement you can get out of a certain type of vehicle. Then you hit a wall. Not everyone wants to buy a little economy car because it doesn't suit their needs. Plus all the added technology to vehicles increases the weight.
Cars in the 80s were a lot lighter and some got better mileage than vehicles just a few years ago. l looked at old road tests where they did a highway mileage tests and was surprised at how little improvement there has been over the last 30 - 35 years. Plus the prices weren't crazy like they are now.
If you want all the bells and whistles, it's gonna add weight and subsequently hurt mileage and emissions as well.
I've often wondered what mileage a vehicle would get if they constructed them more basic?
Just wondering .

 

It's pretty obvious, isn't it? My 1991 was an XtraCab with a 22R-E and weighed almost 500 lbs less than my Access Cab 2008 with a 1GR. The trucks are heavier for a lot of reasons, of course bigger, more substantial cabs for sure, more accessories, more safety stuff, etc. I wish they weren't bigger, I miss the small size of my 1991. I also miss the much better visibility from it. It had a taller windshield and bigger windows, smaller pillars. But I also know in a roll over the roof would end up flat on the floor.

I thought something similar not long ago. Imagine if they built the FJ62, FZJ80 or a mid-1990s Hilux/Pickup/4Runner with today's manufacturing capability. The simpler designs built to excellent tolerances, they'd run forever.

 

Sparky, Neither you or the OP has presented any evidence that Toyota's recommended oil is subpar. There has been a lot of opinion, and a lot of "this is how they do it in Australia" though. Very interesting.

As I said before, I choose to follow Toyota's recommendation. No matter how loudly an internet expert thumps his chest, I'll still follow Toyota's recommendation. BTW, it bothers me not for you to call me ignorant.

 

You're not wrong for following the book, it's always the best, right starting point.

I'm as big a fanboy of Toyota as most anyone but they are not perfect and they don't operate in a vacuum. And honestly since replacing my 1991 with this 2008 I know Toyota is subject to regulation and profit goals as much any other company. So they make engineering and business decisions in the current reality.

Everyone knows this intuitively. That's why we change suspension, change bumpers, change skid plates, change radios, add aux lights, put on sliders, whatever it is to make it yours. We also have to do stuff like replace wheel bearings (which aren't even serviceable anymore, I repacked but didn't have to replace mine on the 1991 several times in 300,000 miles) and ball joints sooner than we used to, worry about frame corrosion constantly. This is because Toyota is building a truck to meet a profit target.

Don't neglect that Toyota doesn't make as much money if your truck lasts 25 years as they do if it only lasts 15. Do they build them intentionally not to last? Maybe. Planned obsolescence isn't a theory, it's called product lifecycle analysis. If they see most of their customers trade-in trucks every 5 years then what's the point of selling something that lasts 10?

Personally, I can only draw upon what I've experienced and seen, which is Toyotas and Hondas and Subarus out there with hundreds of thousands of miles mostly have come from a time before 0Wxx was recommended, so that's why I decided it's not for me. When I see a company recommending 5Wxx in a vehicle built literally right next to mine but going to another country (speaking of our Subaru Forester, which was built in Japan) getting a recommendation that supports my prejudice/bias/opinion then I start to wonder if there is actual reason to think they are using 0 weight oil just to meet CAFE.

If in 10 years there's not a bunch of worn out 2GRs then my opinion will change. People on this thread have just as legitimate argument for deviating as you do for not. In the end it's not zero sum, for you to be right we don't have to be wrong. It might not make any difference, we'll just have to see. Maybe the quality of oil being so much better now and tolerances being better really do make it a moot point.

 

Judging by this evidence

From Toyota, it can be applied that 5w-30 is not up to par in temperatures above 50 F. Now who knows, maybe in Australia they have longer oil change intervals, which could be why they show that for 5w-30, as using it for a long time with out changing the oil 5w-30 may break down faster than a 10w-30 oil in heat.

Bottom line, you want to follow whats on your oil cap what ever trips your trigger you go for it. The point of this thread is to show that your motor is not going to nuke itself from using a thicker oil, and it is in fact designed to handle it.

I have seen plenty of oil analysis reports from people running 5w-30 and even longer OCI and their reports show flying colors in terms of wear on the motor.
Would there be less wear with a thicker oil, most likely yes, but it depends on the usage environment. If you put 20w-50 in your truck and only drive it in freezing temperatures then sure 5w-30 would have less wear.

Bottom line the graph from outside the US is the same motor and the same company. Follow either one to your liking. And do research on carb/cafe. They are frauds mostly.

 

Question?

If I live in Utah, summer can be above 100 and winter can be below freezing. What oil would I run in the summer vs what in the winter if my concern is less mileage and more wear and tear. Also note I'm supercharged.

Thank you, just starting to get confused with all the back and forth.

 

0W oils aren't the bogeyman here in my opinion. If you live somewhere where it gets really cold, a 0W30 is going to give you more cold start protection than a 5W30 while having similar (not necessarily identical) characteristics at full operating temperature.

The 5W20 and 0W20s are what actually bother me the most.

I live in a part of the country where we get extreme cold and hot. I'm going with full synthetic Mobil 1 0W40 moving forward. Should be even better cold start protection than 5W30 as well as better protection on hot days.

5W40 or 5W50 may also be right up your alley if you feel like the engine turns over easy on cold days where you live.

 

To add a bit more to this (being you are supercharged) my buddy just traded his Raptor for a Roush Supercharged F150 with the 5.0 yesterday.

The factory oil spec on the 5.0 in the F150 is 5W20, but Roush drains that and refills with 5W50. They even changed the cap to a 5W50 cap. No internal changes to the engine, not even a new oil pump gear.

 

the 3.4l in 1st gens had big time issues with the superchargers if they weren't running additional fuel mods (7th injector, methanol, bigger injectors, etc.). Mine had pretty bad pinging issues before the 7th. Unfortunately I've read of quite a few accounts of some 3.4ls grenading from being run too lean too hard.

 

Supercharged ones yeah, running lean will kill any motor no matter how reliable it is

 

Why would everyone not want to run 0w-40 or a 5w50, is it kind of like the further between the numbers the less performance? What I mean by that is jack of all traits is a master of none? Does a 5w-30 perform better at say 75 degrees than a 5w-50?

 

Depends on the engine and what you're doing with it.

5W-30 is just fine for moderate temps. But if you're towing with your truck or tracking your car, what matters is the oil temperature itself, not the ambient temp.

My GT350 for example, you'll routinely see 250°F or higher when you're really beating on it on a warm day. It takes 5W-50.

ETA: To elaborate on this, and I can't remember the specifics so I probably have the numbers wrong, but a XW-30 at say 200°F is going to have about the same viscosity as an XW-40 at 220°F. Viscosity drops with increased temp, and a higher/heavier weight oil will have better viscosity at higher temps. It may also be too thick at lower temps for efficiency.

 

So I want to revisit this for a moment - with Toyota's VVT, the cam advance/retard doesn't vary with oil pressure in the same way that an impact gun isn't turned on and off by varying the air pressure.

The oil pressure (or air pressure in the case of the impact gun) is just there as the motive force. What's actually changing the advance/retard on the cams is an electronic solenoid that's controlled by the ECU, just as there's a valve actuated by the trigger in your air impact gun that lets air into the motor to start it turning.

As long as the oil pressure is adequate, the system will work. The thicker your oil, the more pressure you have.

There is far more range in oil viscosity (and thus pressure) for a single oil like 5W30 between 0°F and 200°F than there is between a variety of oil weights like 5W30, 10W40, and 15W50 that are all at the same 200°F operating temp. And all of those oils are going to have much higher pressures until they get up to temp.

If anything, too light of an oil (or too low of oil pressure due to wear) will cause a VVT system to fail. I haven't heard of this in Tacomas, but take a gander at the three valve modular engines in F150's and oh boy...

 

I reviewed some used oil analysis reports for the 1GR-FE running 0W20 on the bobs the oil guys forum as well as on here and decided to experiment with it myself.

My own reports have backed up what I saw - no evidence of accelerated wear. I also don't tow heavy or put in severe duty miles - if I did I would probably adjust my oil weight accordingly, or may test more often to see if it's needed.

Why not be data driven instead of getting emotionally attached to a particular weight of oil?

 

Yeah, it was also probably influenced by anticipated operating conditions, availability of the grade of oil, and consumer willingness to pay for a quality oil vs. whatever is cheap.


Do you have examples of damage caused by running lighter weight oils in these trucks? Seems most come off the road for other reasons than internal engine wear - and when they do it's more often head gasket failure not related to lubrication issues.

 

If toyota could rec 0w-20 safely they would. it would net the best mpg, they even changed the 2tr-fe's oil from 5w-30 to 0w-20 around 2009 if I remember correctly. Not telling you what oil to use, but I would def get it tested often if you are going to run 0w-20

 

Time for an update: as mentioned previously, I'm switching to 0W-40, specifically Mobil 1 FS ECF.

This particular oil gets rave reviews on BITOG and has a lot of fans, including many converts from 5W-30 in other vehicles.



After doing the oil change with 0W-40, my engine exploded immediately. Tullie D, you can stop reading here.

Actually what happened is pretty much nothing. The engine sounds and feels quieter/smoother, but it generally did after every 5W-30 oil change as well. It's really tough to say whether it's quieter than the last time I poured fresh 5W-30 in given that was about nine months ago. I feel like it's the quietest it's been in a while, but that could be confirmation bias sneaking in. I have about 300 miles on the oil as of right now.

Regardless of how I feel about the sound of the engine, I did a used oil analysis on the 5W-30 that I drained out:



It is worth noting that this particular 5W-30 had thinned down well into the middle of the 5W-20 range by the 5,000 mile mark. This is not uncommon and every multi-weight oil loses viscosity over time.

When I come up on 50,000 miles, I'll do another oil analysis on the 0W-40 and we'll see where the chips fall. Based on my driving habits, that won't be until about March of 2020.

I track my fuel economy with Fuelly and we'll also see if there is any discernible change in my MPG.

Edit 4/26/25: restored photos.