AAA study on the effects of different fuel additive packages/fuel brands

[Papa Popov]

https://www.aaa.com/AAA/common/AAR/f...ull-Report.pdf

Recently came across this (surprisingly scientific) study by AAA from 2016 that tests the effects of fuels that do and do not meet the TOP TIER fuel program standards. For the uninitiated, refineries are only required by law to meet EPA LAC (lowest additive concentration) requirements set way back in '96. The TOP TIER program is a LAC standard was created by manufactures (BMW included) for modern day engine tech.

TL;DR: AAA test 6 different fuel brands, (3 that meet TOP TIER standards, and 3 that do not) by strapping a "Ford 2.3L port fuel injected engine" on a dyno and simulated highway driving for 100hrs/4000 miles with each fuel. (Not sure what planet this testing was done on, but it sure as hell wasn't earth if "highway driving" means 40mph.) Carbon deposits were then measured on the intake valves, piston top, and cylinder

Results: Average deposit weights were as follows (from sec. 4.3, pg 15):

Intake Valve
Non-TOP TIER: 660.6mg
TOP TIER: 34.1mg

Piston Top
Non-TOP TIER: 569.7mg
TOP TIER: 526.3mg

Cylinder Head
Non-TOP TIER: 736.4mg
TOP TIER: 893.8mg

Total deposits for each fuel tested
Non-TOP TIER 1: 2401.3mg
Non-TOP TIER 2: 1856.7mg
Non-TOP TIER 3: 1723.2mg
TOP TIER 1: 1502.2mg
TOP TIER 2: 1374.0mg
TOP TIER 3: 1486.5mg

Sample sizes of fuels used could've (read: should've) been larger, but the results for the intake valves are pretty black and white. Results for piston top and cylinder head deposits are up for discussion, as the data for skewed on both sides.

It is also worth noting that switching to TOP-TIER brands can "reduce existing deposits that have accumulated over time over the course of a few thousand miles" (6.3, pg. 22)

NGL, I'm guilty of filling up at the cheapest station in town regularly. I'm in the N52 camp, but having spent the last 6 months trying to solve a rough idle on cold start and a bit of a stutter when going WOT, I'm now convinced the extra few pennies per gallon are worth cleaning up the intake valves. I'm willing to bet that investing in TOP TIER fuels would cut back on how often the N54/N55 guys have to nut on their valves.

[Gangplank]

Originally Posted by Papa Popov

https://www.aaa.com/AAA/common/AAR/f...ull-Report.pdf

Recently came across this (surprisingly scientific) study by AAA from 2016 that tests the effects of fuels that do and do not meet the TOP TIER fuel program standards. For the uninitiated, refineries are only required by law to meet EPA LAC (lowest additive concentration) requirements set way back in '96. The TOP TIER program is a LAC standard was created by manufactures (BMW included) for modern day engine tech.

TL;DR: AAA test 6 different fuel brands, (3 that meet TOP TIER standards, and 3 that do not) by strapping a "Ford 2.3L port fuel injected engine" on a dyno and simulated highway driving for 100hrs/4000 miles with each fuel. (Not sure what planet this testing was done on, but it sure as hell wasn't earth if "highway driving" means 40mph.) Carbon deposits were then measured on the intake valves, piston top, and cylinder

Results: Average deposit weights were as follows (from sec. 4.3, pg 15):

Intake Valve
Non-TOP TIER: 660.6mg
TOP TIER: 34.1mg

Piston Top
Non-TOP TIER: 569.7mg
TOP TIER: 526.3mg

Cylinder Head
Non-TOP TIER: 736.4mg
TOP TIER: 893.8mg

Total deposits for each fuel tested
Non-TOP TIER 1: 2401.3mg
Non-TOP TIER 2: 1856.7mg
Non-TOP TIER 3: 1723.2mg
TOP TIER 1: 1502.2mg
TOP TIER 2: 1374.0mg
TOP TIER 3: 1486.5

Sample sizes of fuels used could've (read: should've) been larger, but the results for the intake valves are pretty black and white. Results for piston top and cylinder head deposits are up for discussion, as the data for skewed on both sides.

It is also worth noting that switching to TOP-TIER brands can "reduce existing deposits that have accumulated over time over the course of a few thousand miles" (6.3, pg. 22)

NGL, I'm guilty of filling up at the cheapest station in town regularly. I'm in the N52 camp, but having spent the last 6 months trying to solve a rough idle on cold start and a bit of a stutter when going WOT, I'm now convinced the extra few pennies per gallon are worth cleaning up the intake valves. I'm willing to bet that investing in TOP TIER fuels would cut back on how often the N54/N55 guys have to nut on their valves.

I've been using Top Tier gas brands for years. My car just runs smoother on Shell, Chevron or other top tier vs low budget gas brands.

[Papa Popov]

Originally Posted by Gangplank

I've been using Top Tier gas brands for years. My car just runs smoother on Shell, Chevron or other top tier vs low budget gas brands.

I should've been running it all along, but I never thought that the difference was significant enough to pay for, especially when I was driving 350mi/week before WFH started. Turns out these companies' marketing departments aren't completely FOS after all

[iminhell1]

The head data is really confusing.
Was there and fuel consumption data tagged to each?
Just a quick look i don't see any.


Why is it the test mule is always a Ranger engine? LOL

[gjm120]

I think cars with direct injection don't see the intake valve benefit. Your valves don't get doused with fuel like a port injection system.

[Papa Popov]

Originally Posted by iminhell1

The head data is really confusing.
Was there and fuel consumption data tagged to each?
Just a quick look i don't see any.


Why is it the test mule is always a Ranger engine? LOL

If you look at the data, there was an outlier on the non-TT side for piston top data, and an outlier on the TT side for the head deposit data. This was why I mentioned the need for a larger sample size.

Only mention of fuel economy was the potential negative impact (2-4%) due to carbon deposits.

Originally Posted by gjm120

I think cars with direct injection don't see the intake valve benefit. Your valves don't get doused with fuel like a port injection system.

"...But along the way to the combustion chamber, that gasoline provides the additional benefit of serving as a solvent that cleans the intake port and intake valve. At least, it used to on carbureted and port fuel injected engines."

"...There are good reasons for doing it this way. Gasoline direct injection lets engine designers account for practically every molecule of gasoline going into the engine so they can extract the most energy and produce the least possible pollution.

These are worthwhile achievements, but it also means that none of those molecules are touching the intake valves on their way to incineration in the combustion chamber. Intake valves have seals on them that keep oil lubricating where they meet the camshaft or rocker arms that press the valves open from running down their stem and dripping into the intake port.

However, no matter how good they may be, a tiny bit of oil still makes its way past and runs onto those intake valve stems. Valvoline engineer Michael Warholic reports that Valvoline regularly inspects the insides of engines with a borescope, and what they are finding is disconcerting, “It's likely you'll see a small amount of oil running down the sides of the valve,” he said. Without gasoline washing them clean, that oil can bake onto the valve and accumulate into carbon buildup."

https://team.valvoline.com/diy/truth...carbon-buildup

[Papa Popov]

Originally Posted by gjm120

I think cars with direct injection don't see the intake valve benefit. Your valves don't get doused with fuel like a port injection system.

Originally Posted by Papa Popov

"...But along the way to the combustion chamber, that gasoline provides the additional benefit of serving as a solvent that cleans the intake port and intake valve. At least, it used to on carbureted and port fuel injected engines."

"...There are good reasons for doing it this way. Gasoline direct injection lets engine designers account for practically every molecule of gasoline going into the engine so they can extract the most energy and produce the least possible pollution.

These are worthwhile achievements, but it also means that none of those molecules are touching the intake valves on their way to incineration in the combustion chamber. Intake valves have seals on them that keep oil lubricating where they meet the camshaft or rocker arms that press the valves open from running down their stem and dripping into the intake port.

However, no matter how good they may be, a tiny bit of oil still makes its way past and runs onto those intake valve stems. Valvoline engineer Michael Warholic reports that Valvoline regularly inspects the insides of engines with a borescope, and what they are finding is disconcerting, “It's likely you'll see a small amount of oil running down the sides of the valve,” he said. Without gasoline washing them clean, that oil can bake onto the valve and accumulate into carbon buildup."

https://team.valvoline.com/diy/truth...carbon-buildup

I'm an idiot, gonna agree with you on this one. Hard for gas to clean valves when it doesn't touch them. Gonna blame the couple of beers I had for this one...

[Gangplank]

Originally Posted by Papa Popov

https://www.aaa.com/AAA/common/AAR/f...ull-Report.pdf

Recently came across this (surprisingly scientific) study by AAA from 2016 that tests the effects of fuels that do and do not meet the TOP TIER fuel program standards. For the uninitiated, refineries are only required by law to meet EPA LAC (lowest additive concentration) requirements set way back in '96. The TOP TIER program is a LAC standard was created by manufactures (BMW included) for modern day engine tech.

TL;DR: AAA test 6 different fuel brands, (3 that meet TOP TIER standards, and 3 that do not) by strapping a "Ford 2.3L port fuel injected engine" on a dyno and simulated highway driving for 100hrs/4000 miles with each fuel. (Not sure what planet this testing was done on, but it sure as hell wasn't earth if "highway driving" means 40mph.) Carbon deposits were then measured on the intake valves, piston top, and cylinder

Results: Average deposit weights were as follows (from sec. 4.3, pg 15):

Intake Valve
Non-TOP TIER: 660.6mg
TOP TIER: 34.1mg

Piston Top
Non-TOP TIER: 569.7mg
TOP TIER: 526.3mg

Cylinder Head
Non-TOP TIER: 736.4mg
TOP TIER: 893.8mg

Total deposits for each fuel tested
Non-TOP TIER 1: 2401.3mg
Non-TOP TIER 2: 1856.7mg
Non-TOP TIER 3: 1723.2mg
TOP TIER 1: 1502.2mg
TOP TIER 2: 1374.0mg
TOP TIER 3: 1486.5mg

Sample sizes of fuels used could've (read: should've) been larger, but the results for the intake valves are pretty black and white. Results for piston top and cylinder head deposits are up for discussion, as the data for skewed on both sides.

It is also worth noting that switching to TOP-TIER brands can "reduce existing deposits that have accumulated over time over the course of a few thousand miles" (6.3, pg. 22)

NGL, I'm guilty of filling up at the cheapest station in town regularly. I'm in the N52 camp, but having spent the last 6 months trying to solve a rough idle on cold start and a bit of a stutter when going WOT, I'm now convinced the extra few pennies per gallon are worth cleaning up the intake valves. I'm willing to bet that investing in TOP TIER fuels would cut back on how often the N54/N55 guys have to nut on their valves.

BTW n55 don't need walnut blasting or a catch can. Not sure how BMW resolved the issue but the new design motor doesn't nee it.

I know the fuel doesn't go over the valves to clean them in a direct injection motor but I find that the car runs noticeably smoother when I use Shell, Chevron, BP or other top tier gas. This was especially the case when I had my 545i & X5 4.4 v8 motors. With the turbo n55 it's not quite as noticeable but still there the motor just idles smoother and runs better.

[gjm120]

Using the attached and a little math you can probably make your own top tier fuel by mixing in a small dose of Techron with each fueling.

[NVHoo]

Results for non-top tier may not apply to California. Thought I read somewhere that all gas sold in CA had to meet the top tier spec by law even if it was not a top tier name brand. Part of their emissions regulations.

[Esteban]

Originally Posted by NVHoo

Results for non-top tier may not apply to California. Thought I read somewhere that all gas sold in CA had to meet the top tier spec by law even if it was not a top tier name brand. Part of their emissions regulations.

A quick Google search found this:

https://www.energy.ca.gov/sites/defa...e_Report_0.pdf

Interesting, but not really conclusive.