Noack Volatility between 9% and 10% sub-par, acceptable or optimal in a TGDI engine?

[Big O Dave]

Is there really a practical, real-world difference between an oil that yields results in this range versus an oil that is in the 6% range?

Are intake valve deposits going to be noticeably greater?

Are there other considerations that would cause an educated oil enthusiast to definitely exclude an oil in the 9% - 10% range from consideration?

 

[burbguy82]

Some here say no. Some say yes. I say both. Depending on engine design, OCI, usage, etc. But for a modern GDI with no wash over the valves, yes. 100%

I would choose the oil with the lowest NOACK possible within the viscosity range you want. It seems the more friction modifiers present, the higher the NOACK...........typcail 0w40 has a much higher NOACK than say 10w30 or 15w40

IMO a dual rated diesel oil of SP minimum would be a great place to start.

 

[AEHaas]

Lower NOACK is generally better but perhaps the fuel is more important. I was recently told by an insider that Shell PREMIUM gasoline has additives that will help prevent deposits the best. 'Not sure of the mechanism.

ali

 

[ZeeOSix]

Don't see how fuel type would affect intake valve deposits in a purely gasoline direct injected engine. In a port injected or dual injected engine, yes.

Lower Noack oils produce less oil vapors., so should mean less vapors going into the intake manifold that could deposit on intake valves. I'd also look into a good PCV catch-can.

 

[shortyb]

Some here say no. Some say yes. I say both. Depending on engine design, OCI, usage, etc. But for a modern GDI with no wash over the valves, yes. 100%

I would choose the oil with the lowest NOACK possible within the viscosity range you want. It seems the more friction modifiers present, the higher the NOACK...........typcail 0w40 has a much higher NOACK than say 10w30 or 15w40

IMO a dual rated diesel oil of SP minimum would be a great place to start.

This.

I don't know about other engine designs, but at least VW (VAG products) it really comes down to how engine oil vapors are handled. There are a several different designs/revisions of breather/oil separator/crankcase pressure valves that play an important part in how much enters the intake stream and possibly precipitates on the valves.

The fuel amount that reaches the intake valves on a GDI is going to depend on if the valves ever go into overlap or open during a compression cycle to push some fuel mist back into the intake side of the engine. Most don't for emissions and economy reasons, but there are some that do. The VW EA888 Gen 3B (Budack) is one that can to a degree. Having an oil with lower Noack can POSSIBLY lower the chances the oil vaporizes and these vapors then get transported around. But generally, it is more desirable to have a lower Noack for overall deposit control from vaporized oil.

 

[Patman]

Don't see how fuel type would affect intake valve deposits in a purely gasoline direct injected engine. In a port injected or dual injected engine, yes.

Lower Noack oils produce less oil vapors., so should mean less vapors going into the intake manifold that could deposit on intake valves. I'd also look into a good PCV catch-can.

If the gasoline you use exclusively in a direct injected engine has a lot of detergents such as Costco gas or Shell V Power I still believe that it will result in less IVD occurring in the first place.

 

[Hohn]

NOACK is an important part of engine cleanliness, but it's only part. There's more to it.

The biggest factor in GDI or TGDI intake cleanliness is crankcase pressure and piston ring sealing. If you have very little blowby and very little crankcase pressure, than you have very little flow into the intake through the PCV system. And so the content of that PCV system matters much less.

I had an IS250 that was an early GDI-only engine and was one of the worst engines ever made for GDI deposits. Toyota had a TSB on it that actually caused them to replace long blocks under warranty it was so bad. Look up the 4GR-FSE 2.5L V6.

My car had 107k on it when I bought it and I drove it until it had 188k over a span of about 10 years. When I bought the car, the intake had barely any varnish, never mind any thick carbon goo. When I sold it, it was still running great without every having to tear into the top end and chisel out a bunch of carbon. Never had a catch can or anything. The engine was good because it had very low crankcase pressure and low blowby.


Once you get a significant amount of PCV flow then the content of that flow matters. NOACK carries vapor but crankcase vapors also have a lot of aerosols. Aerosol is liquid oil in tiny droplets that behaves like a vapor even though it's not. Aerosolization is one of the biggest downsides to low viscosity oils. Thicker oils have larger droplet sizes and resist aerosolization much better.

Putting aside aerosol, you are left with actual vapors. Oil vapor but also fuel vapor from blowby and poor ring sealing or just a cold engine. The vapor part is why your fuel's detergency matters, fuel vapor carries detergents and such with it. This affects the deposit forming tendency of that fuel vapor fraction.


So if you are really worried about GDI intake valve deposits and you already have an engine with very good ring seal, the best way to keep it free of deposits is to use the thickest oil it can stand and use the best fuel you can find in terms of detergency.

 

[Hohn]

If the gasoline you use exclusively in a direct injected engine has a lot of detergents such as Costco gas or Shell V Power I still believe that it will result in less IVD occurring in the first place.

Agree, fuel doesn't all get burned. And the unburned part that ends up diluting oil and/or mixing with crankcase vapors and such really does matter, I think.

 

[shortyb]

Agree, fuel doesn't all get burned. And the unburned part that ends up diluting oil and/or mixing with crankcase vapors and such really does matter, I think.

There has been support of this theory lately from one of the larger fuel suppliers (I can't remember which one, Shell?) where the detergency present in the fuel does in fact reach areas through blowby/crankcase pressure vaporization where it can be effective, ie; intake tract.

 

[thetricky]

Don't see how fuel type would affect intake valve deposits in a purely gasoline direct injected engine. In a port injected or dual injected engine, yes.

Lower Noack oils produce less oil vapors., so should mean less vapors going into the intake manifold that could deposit on intake valves. I'd also look into a good PCV catch-can.

This. I cleaned my PCV valve at 59k when I first got the outback and it was a little dirty, sludgy. Since then I have run Amsoil or HPL and at 174k miles the PCV is just as clean as the first time I cleaned it. Less goo in the intake is a win.

 

[GW.]

This. I cleaned my PCV valve at 59k when I first got the outback and it was a little dirty, sludgy. Since then I have run Amsoil or HPL and at 174k miles the PCV is just as clean as the first time I cleaned it. Less goo in the intake is a win.

That’s a good observation!! I agree

 

[McRightclick]

All in all, I'll stick to my dual injection engines

 

[ZeeOSix]

If the gasoline you use exclusively in a direct injected engine has a lot of detergents such as Costco gas or Shell V Power I still believe that it will result in less IVD occurring in the first place.

Agree, fuel doesn't all get burned. And the unburned part that ends up diluting oil and/or mixing with crankcase vapors and such really does matter, I think.

I'd have to see an official controlled study and test data on this theory, and how much fuel dilution makes a real difference. So if it makes a difference, those big fuel diluting engines should have cleaner intake valves.

Agree with the possible valve overlap effect. Even if those things are going on, the less oil vaporization the better, so lower Noack and a PCV catch-can are beneficial.

 

[ZeeOSix]

There has been support of this theory lately from one of the larger fuel suppliers (I can't remember which one, Shell?) where the detergency present in the fuel does in fact reach areas through blowby/crankcase pressure vaporization where it can be effective, ie; intake tract.

I'd be interested in seeing a controlled test of this, and any test data shown on GDI engines.

 

[GI_GRIFF]

So, if you are really worried about GDI intake valve deposits and you already have an engine with very good ring seal, the best way to keep it free of deposits is to use the thickest oil it can stand and use the best fuel you can find in terms of detergency.

I wanted to repeat this that @Hohn said. I also want to add a little bit. Since the new engines come out of the factory already wore out on purpose to allow blow-by, the thicker, higher viscosity oils can possibly offer a little better ring seal, reducing some blowby. NOACK is important, I mean how much carbon deposit is left when the oil you choose to use is left when it burns off? I run 0W-30 or 5W-30 Euro ACEA C3 oils these days. Just so you know, my Toyota calls for 0W-16 in the owner's manual. The Motul 8100 X-Clean+EFE 0W-30 I have been running that I really like has jumped in price $15.00 to $25.00 per 5L jug in the last year, so I am looking around. As far as NOACK goes, if you are willing to spend the $, Red Line 5W-30 and Amsoil Signature series 5W-30 are a couple of the best on NOAK that I see, and they are both USA owned and blended. Otherwise, the Mobil 1 ESP 0W-30 is your best bet, though I don't use it. This particular Mobil has a NOACK<10, USA owned and they are the biggest and sell the most lubricants in the world, so they must do something right. I am sure there are other choices out there, but in my opinion, the lower the NOACK the better, at least use "Top Tier" gasoline and try to make up for the brand-new factory worn out engines with thicker engine oil to help improve the ring seal and reduce the factory designed blow-by. That's all I have for now.

 

[Hohn]

Wore out on purpose to allow blow by from the factory? How do you figure?

 

[ZeeOSix]

Info from Lubrizol.

Noack of info of Euro 3 and Euro 4 motor oils.

The main key to reducing intake valve deposits on a GDI engine is to reduce oil vapors from going into the intake manifold, by using a low Noack and lower SAPS oil, and add a good PCV catch-can.

 

[tired]

Lower NOACK is generally better but perhaps the fuel is more important. I was recently told by an insider that Shell PREMIUM gasoline has additives that will help prevent deposits the best. 'Not sure of the mechanism.

ali

Chevron says the same thing. They have big signs advertising it at my local gas stations.

 

[ZeeOSix]

Chevron says the same thing. They have big signs advertising it at my local gas stations.

It specifically says that with respect to GDI engines? Need to see this sign.

And Mobil says the Advance Clean motor oil will clean an engine in one oil change, lol.

 

[tired]

It specifically says that with respect to GDI engines? Need to see this sign.

And Mobil says the Advance Clean motor oil will clean an engine in one oil change, lol.

I don’t think it does reference GDI engines but I will take a photo for you the next time I pass by one.