O

Out-Of-Phase

Audioholic Chief
I did not refer to the Consumer Reports article in my post. I referred directly to the actual full report in pdf form from AAA.

I'm a learner in life. I try to learn things. I don't automatically know things or believe everything I read. I try to learn from as many sources as I can for accuracy. I'm not (or act like I am) the smartest person in the room.

After reviewing the pdf report, scientific testing wins, but oil company website marketing still does not.
 
mtrycrafts

mtrycrafts

Audioholic Slumlord
... Have you read testimony from refinery fuel truck drivers? Many claim that they have never added anything to the fuel tank in all the years they delivered fuel products to various customers.

I just want the truth that's all.
Your implication is that the truck driver is the one who adds the additive?
That would be hard to believe.
 
mtrycrafts

mtrycrafts

Audioholic Slumlord
...

I'm a learner in life. I try to learn things. I don't automatically know things or believe everything I read. I try to learn from as many sources as I can for accuracy. I'm not (or act like I am) the smartest person in the room.

...
I guess this would not apply to school textbooks? ;)
 
P

pewternhrata

Senior Audioholic
I'm so relieved that you finally read the Consumer Reports article, which quotes the AAA article that finally convinces you. I'm not sure it should convince you though, so just make it a nap. If you actually read the AAA article, they use an older Ford port-injected engine for the testing. Port-injected engines are largely obsolete now, having been replaced by direct-injection engines. Port-injected engines are more susceptible to intake valve build-up because the air-fuel mixture is created at the cylinder head port, and the mixture is then sucked past the intake valve, wetting the top side of the valve. That's where the build-up occurs. In a direct-injected engine clogging can still occur, but it's at the injector not the intake valves, and it takes a lot longer to build up. So the photos in the article and the test results are only applicable to older port-injected vehicles. Are detergents in gasoline still a good thing? Yes. But using a periodic cleaner like Techron or one of its many competitors still looks like a good idea.

Nonetheless, apparently the Top Tier marketing program has some substance to it.
GDI is prone to intake valves coking, no fuel is able to 'wash' them. They coke due to blow by gases and oil being recirculated through the intake. Only proven way to clean is walnut blasting. It's gotten better over the years as changes have been made. Top tier is supposed to burn cleaner, limiting the amount of coking of the valves. Google coked valves and an endless list of frustration will follow.
 
davidscott

davidscott

Audioholic General
Anyone familiar with RXP? Its supposedly was used to clean Air Force jet engines and is available for automobiles. I have used it a few times but never noticed a difference. That might be a good thing.
 
highfigh

highfigh

Audioholic Overlord
Really, you can put additives in your tank that'll do pretty much the same thing. I used Sea Foam in my older truck and it seemed to work quite well.

What I look for is fuel without ethanol added. Really only useful if you store fuel, but it's worth noting.
Or if you want the power you're paying for. The energy density of alcohols isn't as high as gasoline, but at 10%, it's not as big of a loss than it is with more alcohol. ~77Kbtu/lb vs 115Kbtu/lb. The water absorption and phase separation are a huge problem when the fuel tank is vented, as it is on boats & many things with small engines, especially older ones.

I watched a training video from Mercury/Mercruiser and one of the last comments about fuel mentioned the gas starting to go bad after 15 days. I had originally heard that it starts to go bad in 20 days. Even in its demise, it's faster than before. Yay!

The problem I have is with Congress mandating the use of Ethanol as an oxygenator- they just don't want to listen when industries tell them it's a bad choice and give them the reasons.
 
highfigh

highfigh

Audioholic Overlord
Similar to Chevron's Techron?
Sea Foam, similar? Kind of. They advertise it as a good internal engine cleaner, too- they recommend adding a bit before an oil change, similar to Marvel Mystery Oil. The crankcase is where a lot of deposits end up, but if the oil is kept clean, it doesn't do as much damage. I have been a boat service tech and oil that's as black as coal isn't rare- people seem to think they can get years from one oil change. I use Sea Foam or Techron when they're on sale (the price has gone up drastically in the last few years, or I'm just remembering the price from 20 years ago, not sure which but the increase seemed sudden) but only notice minor differences. I notice more improvement in fuel economy when I change the oil.
 
GO-NAD!

GO-NAD!

Audioholic Ninja
GDI is prone to intake valves coking, no fuel is able to 'wash' them. They coke due to blow by gases and oil being recirculated through the intake. Only proven way to clean is walnut blasting. It's gotten better over the years as changes have been made. Top tier is supposed to burn cleaner, limiting the amount of coking of the valves. Google coked valves and an endless list of frustration will follow.
That's my understanding. Since direct injection engines have become more common, there have been more and more complaints about buildup on intake valves. On port injection engines - as you alluded to - the fuel/air mixture tends to rinse away deposits on valves before it gets a chance to accumulate.
My mechanic hates GDI.
 
Irvrobinson

Irvrobinson

Audioholic Spartan
That's my understanding. Since direct injection engines have become more common, there have been more and more complaints about buildup on intake valves. On port injection engines - as you alluded to - the fuel/air mixture tends to rinse away deposits on valves before it gets a chance to accumulate.
My mechanic hates GDI.
I can't speak to the situation with all direct injection engines, but every car I own has a device called an oil-air separator which removes the oil sucked into the intake manifold by the PCV system, condenses it, and returns it to the oil pan (or oil tank for dry sump engines). PCV oil is the only possible source of intake valve coking on direct injection cars. I'm only aware of EGR coking for diesels. Doing a couple of internet searches I see that many US domestic vehicles seem to have oil air separators, but clearly Hondas don't, and a search does not reveal factory separators for Toyotas either. Perhaps I've driven German cars for too long, but the not having an oil air separator will cause a lot of long term problems, not just coking. The entire intake manifold will get a coating of oil that will seep behind the intake valves.

I remember installing an "oil catch can", which was essentially an oil air separator, on my 1992 LT1 Corvette. It always amazed me how much oil was in the can every month.
 
Last edited:
P

pewternhrata

Senior Audioholic
I can't speak to the situation with all direct injection engines, but every car I own has a device called an oil-air separator which removes the oil sucked into the intake manifold by the PCV system, condenses it, and returns it to the oil pan (or oil tank for dry sump engines). PCV oil is the only possible source of intake valve coking on direct injection cars. I'm only aware of EGR coking for diesels. Doing a couple of internet searches I see that many US domestic vehicles seem to have oil air separators, but clearly Hondas don't, and a search does not reveal factory separators for Toyotas either. Perhaps I've driven German cars for too long, but the not having an oil air separator will cause a lot of long term problems, not just coking. The entire intake manifold will get a coating of oil that will seep behind the intake valves.

I remember installing an "oil catch can", which was essentially an oil air separator, on my 1992 LT1 Corvette. It always amazed me how much oil was in the can every month.
Wish I could utilize a separator, unfortunately the 'dirty' side of my pcv is built into the block and intake manifold. The 'clean' side is an orifice and almost useless to run one on it. Thanks GM ugh. Typically I vent the clean side to atmosphere in the winter, I get alot more condensation in cold weather. Might run a vented oil cap instead but still doing a little more reading up.
 
O

Out-Of-Phase

Audioholic Chief
"The big disadvantage of direct injection is carbon buildup on the backside of the intake valves. This can throw a computer code, and could result with an engine miss or a ignition failure. The other disadvantage of direct injection is cost. The injector tips are mounted right into the combustion chamber, so the materials of the injector have to be very good quality."
 
Irvrobinson

Irvrobinson

Audioholic Spartan
"The big disadvantage of direct injection is carbon buildup on the backside of the intake valves. This can throw a computer code, and could result with an engine miss or a ignition failure. The other disadvantage of direct injection is cost. The injector tips are mounted right into the combustion chamber, so the materials of the injector have to be very good quality."
The coking of the backside of the intake valves is not a universal problem, but it does appear to afflict many reasonably priced cars. I consider the lack of an oil air separator to be a design flaw in some cars' PCV systems, not an indictment of direct injection. And the benefits of direct injection for increased power and fuel economy are significant. For one thing, direct injection makes the powerful four cylinder turbocharged engines that are so popular now possible. Port injection is an inferior strategy by comparison.
 
GO-NAD!

GO-NAD!

Audioholic Ninja
The coking of the backside of the intake valves is not a universal problem, but it does appear to afflict many reasonably priced cars. I consider the lack of an oil air separator to be a design flaw in some cars' PCV systems, not an indictment of direct injection. And the benefits of direct injection for increased power and fuel economy are significant. For one thing, direct injection makes the powerful four cylinder turbocharged engines that are so popular now possible. Port injection is an inferior strategy by comparison.
While I recognize the benefits of direct injection, I'm still a bit leery. These systems a far more complex than port injection systems and it isn't a free lunch, by any means. The added complexity adds up-front costs as well as more expensive repairs down the road. I just came across this article, which was quite educational:
https://stillrunningstrong.com/car-technology/gasoline-direct-injection/
I had no idea that, while reducing CO2 emissions, GDI actually increases particulate emissions to diesel-like numbers. If I ever end up buying a vehicle with GDI (both of our current vehicles have PFI),I'll install an oil separator. My hope is that by the time we need a new vehicle, going electric will be a practical option.
 
highfigh

highfigh

Audioholic Overlord
While I recognize the benefits of direct injection, I'm still a bit leery. These systems a far more complex than port injection systems and it isn't a free lunch, by any means. The added complexity adds up-front costs as well as more expensive repairs down the road. I just came across this article, which was quite educational:
https://stillrunningstrong.com/car-technology/gasoline-direct-injection/
I had no idea that, while reducing CO2 emissions, GDI actually increases particulate emissions to diesel-like numbers. If I ever end up buying a vehicle with GDI (both of our current vehicles have PFI),I'll install an oil separator. My hope is that by the time we need a new vehicle, going electric will be a practical option.
The EPA and CARB don't care how much it costs to repair an engine, they just want the emissions numbers to match their goals.
 

newsletter
  • RBHsound.com
  • BlueJeansCable.com
  • SVS Sound Subwoofers
  • Experience the Martin Logan Montis
Top