Oil Viscosity, CAFE, and your Taco Engine

It's been five years since I bought my 2014 V6, so now I am the powertrain warranty. This got me thinking - what kind of oil is best for my engine rather than best for the warranty?

I'm old enough to remember when owner's manuals used to specify multiple SAE oil grades depending on ambient temps. All of the cars that I owned that were made in the 90's or earlier would specify more than one oil grade.

This seems to have gone out the window in recent years and by all accounts, CAFE (Corporate Average Fuel Economy) requirements in the US are largely to blame. Toyota isn't alone, as I have noticed Ford and Chevrolet doing the same thing.

People will tell you that it's because "modern engines have tighter tolerances" and plenty of other things that other people have told them. It's malarkey.

As proof, you need to look no further than Toyota's owners manual for vehicles with the 1GR-FE engine outside of the US. This, for example, is from the 2014 Toyota Hilux in Australia:



Obviously, it gets pretty hot in Australia. But it also gets hot in Arizona, and note that the chart specifies a range of temperatures from -20F all the way up to 100F - exact same range as on the US chart!

Contrast that to the US manual for the Tacoma with 1GR-FE:



I also peeked at the owners manual for the FJ Cruiser in AU with the 1GR-FE, and it had the exact same chart as the Hilux.

Now, are there differences between the 1st gen 1GR-FE delivered in AU and elsewhere and the one we get in our 05-15 trucks? Very likely, but I'd bet anything that the bearings and clearances are the same, which is what really matters for oil pressure and such.

For you 2016+ owners, it's much the same story only Toyota now recommends 0W-20. The 2GR-FKS isn't offered (to my knowledge) in any trucks anywhere else in the world, making comparisons difficult. But it is offered in lots of cars - likely with different cams, intake, and exhaust manifold if I were to guess. But it's largely the same engine.

For instance, the Lexus RC 350 uses the 2GR-FKS in both Australia and the US. Helpfully, all RC 350's are built in Japan, so they should be very similar aside from one has the wheel on the wrong side. Here's what the Australian owner's manual recommends:



Compare and contrast to the US owner's manual, which exclusively recommends the same 0W-20 as the 2016+ Taco:



As I mentioned before, this is not exclusive to Toyota. Ford has taken to recommending lighter and lighter oils as well. I'm a Mustang owner, and it seemed odd to me that Ford recommended 5W20 in the high-revving, 430hp 5.0. Guess what they recommend in Australia? 5W30.

When I traded my 5.0 for a GT350 with a 5.2, it wasn't lost on me that the oil spec changed to 5W50. This is on a car with low production (making for a small CAFE hit) that has a gas guzzler tax. But the engines are nearly identical in terms of bearings and clearances. Makes you wonder...

And again - I can predict the typical responses to this. "It gets hot as hell in Australia!" - not any hotter than it does in Phoenix, genius. "Just use what Toyota recommends" - we're literally talking about what Toyota recommends when CAFE isn't in the equation.

I'm not trying to convince you to change oils - depending on your climate, the US factory recommended oil might actually be optimal. Or it can also very likely be a liability.

Sources:

2014 AU Hilux Owner's Manual
2018 US RC350 Owner's Manual
2018 AU RC350 Owner's Manual

Edit 4/26/25: restored photos.

 

The difference between 5w30 and 10w30 in the first chart seems odd. Also if cooling system is working as designed should the operating oil temp be the same for all climates, therefore only the first number is important when starting? I've always heard lower is better for cold starts.

 

Yes - or does it? This was actually a quite common way for manufacturers to spec oil back in the day. I keyed into this on Doug DeMuro's recent vid on the Grand National:



But just because someone else has done it doesn't mean anything.

From research, I believe it's due to the way conventional oils break down. While the 5W-30 and 10W-30 may have similar specs when new at 200°F, after a while the 10W30 is going to offer superior viscosity at operating temps.

This isn't as much of a problem with many modern synthetic blends and full synthetics, and VII's (Viscosity Index Improvers) have gotten better.

I would think of it more as a range of operating temperatures rather than one single operating temperature. Your thermostat opens up at a certain temp, but that's not the highest temp the water can be, right? The range for oil can comfortably span 50 degrees F or so, and while a 0W-20 or 5W-30 may be good enough at 200°F, it might be too thin at 250°F.

I don't know what's typical for my truck when towing on a hot day because I don't have an oil temp guage, but I can tell you that 250° is completely expected in my GT350 on a hot day when you're having some fun. On a cool day, it's difficult to get it up to 200°F at all.

 

It would not surprise me if it all is to meet Government standards

 

After doing more digging, it seems like this is exactly what's going on.

Check out this document from the EPA: http://mycommittees.api.org/lubricants/Past Years Committee Documents/2004 Lubricants Standard/03-18-2004 Lubricants Standard/attach8epaletter.pdf

Scroll down to the second page. There a couple of relevant sections here.

So what we have here is the EPA mandating that if a certain oil is used to obtain the MPG figure that gets plugged into a manufacturer's CAFE score, that both the oil filler cap and owner's manual must specify that oil.

 

This is interesting. I guess I can feel more comfortable putting something like 15w-40 in my motor now. But for the record, I live in california and it gets hot as balls in summer. My 05 tundra with the 1GR has had 5w-30 for it's whole 358,000 mile life. So I would say 5w-30 isn't doing a horrible job keeping the motor happy, but that's not to say that a heavier weight oil wouldn't have protected it better during that period. I wonder if there is even a noticeable MPG difference 5w30 vs 15w40.

 

I see you track mileage on Fuelly, I do as well. I'll be keen to see if I can observe a difference between 5W30 and 0W40. I'm 4000 miles into my 5000 mile interval right now, probably changing oil in a month or two.

 

No need to change the oil that often if you are running synthetic

 

Truck gets idled a lot and I don't drive it a ton. My oil changes are once every 8-9 months these days.

I have been running Motorcraft synthetic blend 5W30.

 

I get my oil analysed, currently running a 14,000 mile oci based upon their recommendation.

 

I do that in my GT350, but it costs more to analyse the oil in my truck than it does to just change the oil.

GT350 oil change is over $100 just for the oil.

ETA: that said, I might send in a sample of the 5W30 after it hits 5k and the 0W40 after it hits 5k this time around just for S&Gs.

 

I sadly just bought 5w30 the other day for my truck. I may go back and buy some 0w-40 or 15w-40 and just save the 5w-30 for my subi. I get my oil tested each change also. I change it around every 4k just because my engine is supercharged so if something bad is happening I want to know sooner rather than later.

 

Question, as my truck gets to about the 5k mark I notice that it seem to tick louder amd not feel as smooth. Once I change the oil, typically around 5k it goes back to being quieter and smoother. Any ideas why it seems to be so drastically change. This was the case with my 13 4.0 6mt with about 88k on the clock using Valvoline oil.

Just got the 15 supercharged pro.

 

OP, thanks for a thought provoking topic.

For your test, I'm going to bet that you will NOT see any MPG difference. There's probably as much or more political behind-the-scenes reasons for the oil spec as there are engineering reasons. I think that either oil will meet the engine's needs just fine.

Myself, I'm not going into Don Quixote mode, battling windmills. It's not worth wasting my time. I'll stick with the recommended oil.

I am interested in what your test turns up though.

 

I've only ever seen the tunrdas grenade motors that are supercharged. We all suspect fuel quality and detonation as the cause.

Big thing with the supercharged motors is staying on top of fuel quality, replace spark plugs consistently and run any quality synthetic. I'd still run 5-30 unless I was lower states above 100 degrees constantly.

 

In the summer it gets hot constantly and I go offroading out in Az so maybe I’ll use it in the summer time

 

To be clear, 15W40 and even 20W50 are recommended by Toyota. Just not Toyota USA.

And I'm not sure how grabbing one jug vs. another is "wasting" your time. Your time must be really valuable if grabbing a jug off the top shelf is too much to fit into a day. You did seem to have enough time to type up a nice long response on here about how you aren't wasting your time though...

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Anyway, the rest of you might ask why I would choose 0W40, and the answer lies in that AU chart in the OP: 15W40 isn't really suitable for cold starts under about 10°F. 0W40 will be very similar to 15W40 at operating temp, but will have much better protection (cold flow) during a cold start, and depending on the particular oil may be even better than 5W30 in the cold.

Where I live, we get the occasional cold snap of -40° and it's a sure thing to see -°20F a few times a winter. In the summer it will get up to at least 100°F and every once in a while we'll see 115°F.

0W40 is a good oil to use year-round for a lot of vehicles and will give you a lot of protection on hot days with high load. Chevrolet just switched to recommending 0W40 in the Corvette after recommending 5W30 for a couple decades.

 

Well, AFAIK, Toyota only has one recommended oil for my 2019 Tacoma V6, and that's 0W20. I'm going to stick with it.

 

Did you not read literally ANY of the OP?

Toyota recommends a variety of oils for the 2GR-FKS outside of the US. Since the Tacoma is the only truck that comes with the 2GR-FKS and it isn't available outside of North America, I looked at the Lexus RC350 which uses essentially the same engine.

Lexus recommends 0W20 in the US for the 2GR-FKS, also. They aren't limited to that recommendation in Australia and the owner's manual reflects that as you can see from the screenshot in the OP.

 

I did indeed read all of the original post. Found it educational in some ways. Toyota built and marketed my Tacoma for the US. I live in the US. Therefore, I'm going to use Toyota's recommended 0W20.

I have not argued with you, or implied that you were wrong. I live in North Carolina. It never gets to -20 or +120. It stays comfortably in this range:



Wow. 0W20 is almost perfect for my use.