finally found the 5w-20 TSB...

[sbergman27]

Originally Posted by TheSilkySmooth

What else?

Yes, all multivis oils are thicker at cold temps than at operating temperature. I mentioned the fact because it is widely misunderstood, and people who do that tend to recommend 10wX oils or straight weights.

I would not expect to be able to measure the difference between AFE 0w30 and a 5w30 without a lot of very systematic testing. I seriously doubt that your 5 mpg difference has anything at all to do with the oil.

Engines don't see EP. They see sliding friction under very high shear conditions. Lot's and lots of it. What, exactly, do you think that extra EP additives are buying you? And what are the down sides, I wonder?

You are, of course, free to second guess the engineers as much as you please. Especially if you are out of warranty. But you do it at your own peril. And I'd be particularly nervous going further and telling *other* people to use it.

That said, if you are looking for an impressive oil that meets a range of European (and particularly German) high performance standards which almost no other does, and has an HTHS of 3.7... look to Mobil 1 0w40. If I were going to stray from the spec'd 5w30, that's what I would use.

http://tinyurl.com/39b6cg

BTW, why don't you care about your (and other people's) catalytic converter?

-Steve

[TheSilkySmooth]

Originally Posted by sbergman27

Yes, all multivis oils are thicker at cold temps than at operating temperature. I mentioned the fact because it is widely misunderstood, and people who do that tend to recommend 10wX oils or straight weights.

I would not expect to be able to measure the difference between AFE 0w30 and a 5w30 without a lot of very systematic testing. I seriously doubt that your 5 mpg difference has anything at all to do with the oil. - Agreed. I have a failing converter and it's attendant high backpressue, also the winter fuel seems worse than last season - though my converter may be confounding diagnosis.

Engines don't see EP. They see sliding friction under very high shear conditions. Lot's and lots of it. What, exactly, do you think that extra EP additives are buying you? And what are the down sides, I wonder? - - I am assuming periodic EP due to piston cocking at stroke ends - though the 1NZ has a designed wrist pin centreline offset to minimise this. Cam loads can get high, but only during valve float caused by oil ash buildup on thier heads and periodic sticking due to infrequent high RPM excursions. Maybe I do want a higher HTHS after all - or maybe just a bit more viscosity. When using oils with > 0.1% EP; My engine uses little oil so I dont worry about converter loading with metal thiophosphates.

You are, of course, free to second guess the engineers as much as you please. Especially if you are out of warranty. But you do it at your own peril. And I'd be particularly nervous going further and telling *other* people to use it. - I would imagine Engineers would prefer no exhaust aftertreatment worries, and more safety margin from the energy conserving lubricant we use. The EP and HTHS was not reduced in North America to benefit the engines or its longevity.

That said, if you are looking for an impressive oil that meets a range of European (and particularly German) high performance standards which almost no other does, and has an HTHS of 3.7... look to Mobil 1 0w40. If I were going to stray from the spec'd 5w30, that's what I would use. - Agreed its EXxon-Mobils' best effort as is The M1 racing 4T superbike oil, but I am no fan of PAO bases where they have no pronounced benefit. I doubt the VVTi hydraulics would allow enough cam advance at lower RPMs with the higher viscosity of a light 40wt - it's overly sensitive and likes an 10-11 cst oil to be in its sweet spot.

http://tinyurl.com/39b6cg

BTW, why don't you care about your (and other people's) catalytic converter? - I care about my converter - but mine usually fail due to suspect incorrect mixture and high heat loading brought on by misformulated E10 fuels - not a pinch of dithiophosphate here or there.

-Steve

Steve , I really appreciate you reasoning

[sbergman27]

Yeah, I had wondered about the vvt-i wrt viscosity. It's one of those little gotcha's that is easy to overlook, and an example of why I'm somewhat disinclined to stray very far from the recommendations. You just never know what esoteric details got discussed during the engine design meetings that you were not invited to. Engines (and oils) have gotten so complicated since when I was growing up in the 60s and 70s and we all just dumped 10w40 into our engines and swore by whichever brand we'd always used.

Though I've tried to keep up through reading, the Yaris is my first foray into current technology on a hands-on basis. I tend to keep my cars for a very long time. My other cars are two 1968 Cadillac Fleetwood Broughams, which I grew up with, and my trusty 1988 Chevy Sprint Metro (really a Suzuki) which is about to turn over 350,000 miles. The Sprint is actually carbureted. Though it *is* an electronic feedback carb, so it has many of the advantages of FI. (Including DFCO, BTW.) But it doesn't support the fun toys like the Scangauge II.

-Steve