The 4 cylinder is reputed to be an aluminum block engine; while the V6 is a cast iron block.

I have the latter engine type, and have found it to be one of the most reliable engines I've ever driven behind.

We have a Camry with the former engine type and, while the reliability of the 4 cylinder block is decent, we currently have an issue with leaking valve guides, resulting in oil burning on a morning start-up, and the engine has only 104K miles on it.

I can't say what you'll run into, but I suspect that the 6 cylinder engine is more appropriately powered to drag-around the weight of the Highlander chassis--particularly given the wind resistance of the higher profiled vehicle at freeway speeds.

 

The head bolt issue is not an "all" I4 issue, it was an issue with a production lot of a certain engine. The engine for some of these I4 Toyotas are the same (Camry, etc.), so the head bolt issue was around for any block of that production lot. Latter manufactures of the same engine did not have the issue. Any aluminum engine will have different issues than a cast iron one, and vice versa. Check to see of that block is in the problem range. If not, you are good to go. If it is, and was not "fixed", then it is a problem that could happen.

Same is true of the oil consumption issue - a certain run of engines for the I4 had the consumption issue, some did not.

I4 is easier to work on many things such as spark plugs, valve cover gaskets, things like that. V6 of course has more oomph, towing capability. I have both I4s and V6's, and find the I4s to be easier to DIY generally.

 

Thanks guys. It appears that this was specific to the 2AZ-FE engines with short block number PR 410-09050.

http://youdiyauto.blogspot.com/2013/08/toyota-2az-fe-stripped-block-threads.html

I will try to find a website where I can get the block number from the VIN somehow.

 

I had one, 2001 Highlander 2.4L AWD with the 2AZ-FE (miss it dearly) and to replace it, a 2005 Lexus RX330 with the 3MZ-FE which is basically what a V6 Highlander would have.

The 2.4L Highlander was a blast to own. I had ZERO of the common 2AZ issues with the engine my entire ownership ~15 years unlike my current Camry which burns oil. But I was always on top of oil and fluids. Only major fixes over 15 years were an alternator, steering rack, and a new catalytic converter. Engine was a bit small for the body but we didn't do anything crazy with it, but on long trips you can see it struggle on hills. AWD was decent, did snow pretty well.

The 3.3L Lexus definitely shows a lot more that the 2.4L lacked (obviously) at the cost of MPG. Also having a timing belt and a hefty bill when that comes around kinda sucks. But it excels in AWD compared to the Highlander and coasts more easily (not even talking about ride comfort just engine strength). Also being a Lexus, much more luxurious than the Highlander.

While I do miss the simplicity and reliability of the HL, the Lexus is growing on me the more I drive it. It just sucks having to care for the car while I basically beat the HL into the ground. But not one day did I have to even slightly have to think my HL wouldn't start or leave me stranded.

 

Have both a V6 and an I4 HL (2001 3.0 and a 2006 2.4) Just over 170k miles on both engines. The 4 doesn't burn more than a pint between OCI (which vary between 5k to 7k miles) while the V6 can use up to a full qt in as little as 500 miles. Both are pretty equal on MPG stying pretty much within 1 mpg of each other. As for performance honestly that little 4 is VERY respectable especially considering the size/weigh of the HL and that it has AWD. I honestly like opening the hood of the 4. Everything is easy to see and work on. The V6 IMO is a nightmare in that regard.
What model year(s) were the 4 cyl engines an issue BTW?

 

Both are pretty equal on MPG stying pretty much within 1 mpg of each other.

Interesting to hear this, my old HL was very good on gas compared to my RX but at the same time Lexus recommends 91+ octane over 87 I used to pour into my HL. Also 3.3 vs 2.4 compared to your 3.0 vs 2.4

As for performance honestly that little 4 is VERY respectable especially considering the size/weigh of the HL and that it has AWD. I honestly like opening the hood of the 4. Everything is easy to see and work on. The V6 IMO is a nightmare in that regard.

This, I did the spark plugs when I first got my RX, what a NIGHTMARE

What model year(s) were the 4 cyl engines an issue BTW?

Camry's and RAV4's were heavily affected. For Camry's 02-04 has the head gasket issue, 05-09 had oil consumption issues. It was just a mess all around. But if you never needed to pull the head or got the engine rebuilt under warranty or keep the oil topped off (like me), the 2AZ's are bulletproof. Almost 200K on the clock on my Camry and we put 150K on the HL before we traded it

Well, per that blog it's the 02-04 Toyota 2AZ-FE I4 short blocks. But then it goes on and says: "Head Gasket on the 2AZ-FE is dual layer steel, thicker at the edges to "give" a little during expansion and contraction. Toyota changed the HG design in 07, adding more metal to the HG (in the area the finger above is pointing to)." So, I assume 05 and 06 engines are also affected?

05-06 engines more so had issues with oil consumption than the head gasket.

 

Well, per that blog it's the 02-04 Toyota 2AZ-FE I4 short blocks. But then it goes on and says: "Head Gasket on the 2AZ-FE is dual layer steel, thicker at the edges to "give" a little during expansion and contraction. Toyota changed the HG design in 07, adding more metal to the HG (in the area the finger above is pointing to)." So, I assume 05 and 06 engines are also affected?

 

Well my 06 does not have any consumption issues. Which is good. As for gasoline our 2001 (the V6) recommends premium also. Honestly I tried it for awhile and it seemed to make no difference in performance or fuel economy that we could track, though it sure made a difference in my bank account. Over a dollar more per gallon! For it to have made sense to use it that HL would need to increase from it's 18 mpg avg to over 50 LOL

 

As to the lower octane options....I have noticed that, when I drop below 91 Octane, I will get a loss of power--slight but detectable to me--on hills or under loading, like towing--particularly when it's hot out. It's just been easier to stick with 91 and just not worrying about potential engine damage from detonation.

Funny.....91 used to be mid-grade gasoline, back in the day. I recall regular being something like 86 or 88, super was something around 101 or 104, with the mid-range octane rating being in the low 90's. Then again, regular used to be 29.9¢ / gallon at my local station, too, with super about a nickle or so more.

 

Because, as I mentioned earlier...

As to the lower octane options....I have noticed that, when I drop below 91 Octane, I will get a loss of power--slight but detectable to me--on hills or under loading, like towing--particularly when it's hot out. It's just been easier to stick with 91 and just not worrying about potential engine damage from detonation.

Just as a matter of habit of travel, I fill up at either Chevron, Mobile, or Shell--these are the stations that are along my daily travel routes--so I get a good feel for the performance of the different grades of gasoline that I've tried. Plugs, injectors, and coils are new, as well as the cats and all four sensors, and I keep the air filter changed a bit more often than is specified, due to the ridiculous amount of dust we have, because of road work pretty much everywhere, lately. I clean the MAF sensor every three air filter changes--just because it's so easy to do.

My daily driving involves romps through city streets, long stretches on the freeway, and hills to climb--because my wife's office is several valleys away from home. Since her health makes it impossible for her to drive, or to take the MetroLink train, I'm the chauffeur. As a result, I do about 250 to 350 miles a-day, depending on what I have to do, with 160 to 180 of those miles devoted to getting my wife back and forth. I already know that I get just about 360 miles out of a full tank--top into the yellow flashing-beeping "feed me!" indicator--so I have a good feel for how often I need to fill-up, and habitually do so when I hit the half-tank mark on the fuel gauge.

If I fill up with regular, or mid-grade, gasoline, I will have problems with loss of power on hills. I know this because that is what has always happened when a station has had an empty premium ground tank, and the top-half of the gauge evaporates quickly enough that I notice it as being abnormal. This has been the way it has always played-out, since I bought this thing, at 79K, in 2012. I don't argue with the vehicle. I just give it what the symptoms say it needs and, from what I can see, I'm actually receiving value from my manner of driving and dealing with the care of this particular vehicle.

I make attempts to prevent problems from cropping-up, and I take care of problems that crop-up when they are small, instead of allowing those problems to grow and cause additional damage and expense. Using the high octane grade of fuel is only one part of that. Another part of it is replacing the alternator at 150K miles--before it fails--as well as doing the timing belt every 85K, and the water pump at around every 180K. Then there's the habit of flushing the power steering and brake system every New Year's day....

Would people criticize me for doing things this way? It seems that the answer would be, "Yes", but I'm the one driving the vehicle, and I know this particular vehicle VERY well, and I am keenly aware of the driving conditions and loads that I am heaping upon it.

So, I do what I do, and feel not the slightest inclination to do otherwise, until some evidence comes along that suggests that I will derive increased benefit from doing otherwise.

Your vehicle is different than the one under my ass, when I start it up at 04:30 every morning. Your road and environmental conditions are different as well--markedly so. When you stop to think about it, even the composition of the gasoline you fill up with is likely radically different from the makeup of the gasoline that I toss into the filler neck of my tank. If I came out to NW Illinois, and stayed for a while, I might find that what you are saying works well for me--while I'm out there.

However, in this environment, under these conditions, with this vehicle, this is what achieves good results for me; and that is what the considered evidence indicates that I should do. I hope that you can see the myriad variables involved, and know that there really isn't a hard-and-fast rule that applies universally to the discussion of whether or not to use the high octane grade.

My different experiences justify taking actions different from yours; and we are both justified in doing what we each see as being best in our different circumstances.

 

Well the owner's manual does not "call" for premium it simply says it "can" increase performance and MPG but will not cause engine damage or any real degradation if regular is used. We tried it in both my daughter's Lexus ES330, and my HL V6 neither showed any increase in performance or economy, so IMO when you're looking at over $1.00 per gal difference it makes no sense to use premium. At our local Circle K they even have a so called non-ethanol option which is also quite expensive compared to plain old E10. Here too I tried it in my own car the 4 banger and it did nothing. Actually if anything I had reduced MPG. So why pay more for less? I do buy it for my small engines though, but quite frankly it has an odor to it that makes me think there are some pretty awful oxygenates in there. Maybe MTBE, Methanol, Ether what have you and quite honestly I have seen FAR more harm to fuel systems from those chemicals than Ethanol

 

$1.00/Gallon more for premium?

OK....that's insane. Price differential, out here is only a dime.

 

$1.00/Gallon more for premium?



OK....that's insane. Price differential, out here is only a dime.

It’s typically a dime in Calif, but a few weeks ago we saw a station somewhere that was a dollar diff. My wife and I were quite surprised.

 

That's when it's good to have a bottle of 104+ in the cargo tray...something I started doing after running into the crap gasoline that they were slinging in AZ, a few years back.

 

Things must be pretty bad in IL, then. Seriously, out here in SoCal, it's a dime differential between grades of octane content; which means that we're paying butt-loads more for regular than you folks are. On a bad week, Premium is $3.89 / gallon; with mid-grade being $3.79 / gallon, and regular going for $3.69 / gallon.....if you pay with a card.

I'm not sure what the drop is for paying with cash, but I think it's something like 25¢ less, across the board.

So, yeah, I use premium because the price difference isn't even worth debating.

 

Spread here is from regular about $2.60 to premium running right around $3.50 so like I said none of our V6 model cars perform any better or return any better MPG to make premium worthwhile and actually see no improvement on it what so ever. In both V6 vehicles the owner's manual does not state "premium is required" it says you may notice slight improvement if you use it. Whenever I have seen a vehicle that required premium there is always a red sticker inside the gas door. The Highlander and the Lexus do not have those stickers. Not even a "premium recommended" sticker. So why pay for something that A. is NOT required and B. has no benefit?

 

Nope it is definitely burning it.

 

Thankfully no oil consumption issue on my 06 4 cyl. In a 5 to 7k OCI I only end up adding about 1/2qt total. I am kind of anal about oil levels. If it's the slightest bit down I add a little. I know probably over kill

 

Maaaaaybeeeee......but....

It keeps you under the hood regularly; which means you get to keep the name.

 

That name came from the repair business my late friend and I ran (he passed away over 13 years ago). We did a Chrysler oriented shop geared primarily to the mini van.

 

I am going to look into this further, then.

My dad's '06 Camry has just started the blue smoke at start-up--no visible oil smoke at any other time--and I really need to take care of it, short of replacing the head in its entirety, because I don't have time to waste on a lot of little "maybe it's this" or "maybe it's that" which will consume the time that I need to spend re-roofing the house. LOL