*Tech Talk* Low-viscosity Oil in 1NZ-FE

[Lux]

Hi Yaris World

I have a few technical questions for the gear heads around here. This is intended for highly experienced service technicians and engine builders.

I am experimenting with the use of low-viscosity (0W-20, 5W-20) motor oils for my 1NZ-FE engine for further reduction of parasitic loss (short of knife-edging the crankshaft). I want to ask for some information regarding the mechanical limitations of the NZ engine's lubricating system. My main concerns are with the oil pump, journal and bearing tolerances, valvetrain, VVT-i phasing, and changes in oil pressure.

I know that, by design, the engine is intended for the use of 5W-30. What I'd like to know is whether the journal/bearing clearances will tolerate thinner oil under all conditions... I'm talking about cold start (dry bearings) to extreme-duty race loads. Chemical thermostability is a non-issue as I will use full synthetic oil.

Will the cam phaser be affected by a low-viscosity oil? Has anyone noticed the engine knocking on a cold start (zero oil pressure) due to inadequate viscosity? Any further insight into using 20-weight motor oil on these engines?

This isn't isn't a typical drain & fill question, I'm interested in the science behind viscosity versus the NZ sump system.

Thanks!

[fnkngrv]

Toyota mandated a few years ago that you could change to 20 weight without an issue. I have used 20 weight for 3 years now in both Northern Maine subzero weather and also in Alabama's hot temps. I never encountered issues in regards to knocking or otherwise. This is with Mobil1 and then AMSOIL.

[Hershey]

Here's an U.O.A. for 5w-20 from the '08 sedan . Column 1 is Shell 5w-20 syn , 2 is Shell 5w-30 syn and 3 is Pennzoil conventional 5w-30 . All are SN/GF-5 . Not an expert , but the numbers look good . Slight increase with TIN , up 1 . See here for TIN and other metals , etc. , http://www.bobistheoilguy.com/engine-oil-analysis/ . Just drained second fill of the Shell synthetic 5w-20 and went to Shell 5w-30 syn.. There's a Toyota Genuine Motor Oil viscosity chart for Canada and it's the real deal . Got confirmation . Here it is , http://pdfcast.org/pdf/toyota-oil-recommendation .

[Lux]

That Toyota oil viscosity chart is a pleasant surprise to me. I know the NZ engine is an ageing design, so I didn't suspect that they'd approve 20-weight oil so readily. I reckon if Toyota says it's OK, then I will go ahead with it.

What is your experience with using synthetic gear oil in the gearbox? Currently, I'm not experiencing any shifting issues, but I just thought the action should be smoother than my other cars, even at operating temperatures. I've used MT-90 heavy duty shockproof gear oil in my other car with good results. What do you folks say?

[fnkngrv]

^ I noticed a big difference in shifting into reverse as many others have by switching to synthetic. I have also noticed better shifting through the gears quickly at high quantity intervals (IE, shifting many times in racing and the city) so in retrospect I have experienced what AMSOIL has stated in regards to gear oil temps running cooler.

[Hershey]

+1 . The Amsoil MTG is a GL-4 . Here it is , http://www.amsoil.com/storefront/mtg.aspx . It's $14.80 a quart . Went up some .

[fnkngrv]

I actually am using the severe gear oil:

http://www.amsoil.com/storefront/svg.aspx

The price of course is less if you become a preferred customer and the better pricing is of course on all of their products.

http://www.ttr-online.com/synthetics...tomer-program/

Preferred customer pricing is $9.50/qt for the standard long life and $11.55/qt for the severe.

[suckerface]

I use a 0w-20 Euro blend oil (I think). I don't recall what brand, but I have a couple bottles in the car, I'll verify tonight. I live on Lake Michigan in WI, and run it year round. Zero problems to date for the 2 years I've used it. Just switched to the Amsoil GL-4 synthetic transmission oil, and noticed a huge difference. It's worth purchasing the 6 month "preferred customer" deal and getting the discount, it'll pay for itself quickly, and you can help friends/family out with the costs you can get too. Hell, charge them retail and make a couple bucks a quart!

[Lux]

Thanks guys for the insight! I've talked to the parts supplier and ordered an entire case of 1-US gallon jugs of motor oil and 2 bottles of gear oil. It'll be some time before it's shipped to me. Thanks again.

P.S.: I've opted for the regular AMSOIL gear oil, being that the severe duty (a.k.a heavy shockproof in other brands) will be more viscous than I need. The 1NZ doesn't produce enough torque and gear load to make use of it anyway, haha

[fnkngrv]

Originally Posted by Lux

The 1NZ doesn't produce enough torque and gear load to make use of it anyway, haha

This is true if you are running it stock