Fuel for older Evinrude/ Johnson

[cyclops222]

Gas companies are always looking for ways to make more profit by cutting corners. I found Seafoam every 3 months returned about 12 % of lost gas mileage.

 

[dingbat]

I found Seafoam every 3 months returned about 12 % of lost gas mileage.

To what do you attribute this increase in performance given that Seafoam is <95% pale oil and naphtha and <25% isopropanal alcohol?

 

[jimmbo]

Only thing I ever found Seafoam good for was, Nothing

 

[Crosbyman]

Seafoam is like vaccines... some believe in them some don't. The are several utubes reporting significant improvements after it's use but who posted such conclusions is never certain.

If it helps free up clogged rings maybe the improved compression helps...who knows.
As long as damages it could create are limited to one's pocket book.

 

[cyclops222]

The modern Fuel Injected Lean Burn engines have a built in problem. The injectors are aimed at the coolest surface of the intake valve. Result is carbon build up on the valve.

 

[Crosbyman]

does not seems to affect ETEC injectors so much as valves. They do get dirty and require shop cleaning when performance heads down but a lot more problems comes from bad gaz gas-water mix dirty old fuel etc...

 

[jimmbo]

That Carbon Build Up on the Valves is from Crankcase Vapours from the PCV. Older FI Engines which sprayed the Fuel upstream of the Intake Valves, didn't have much crude on the Valve Face, because of the Detergents in the Gas washed the Valves. Newer DI Engines actually had an Injector added to spray Gasoline on to the Valves to Keep them Clean.

 

[dingbat]

The modern Fuel Injected Lean Burn engines have a built in problem. The injectors are aimed at the coolest surface of the intake valve. Result is carbon build up on the valve.

Two of my three vehicles are turbo GDI.
I see a slight bump running 93 octane (compression over 10:1) but gas mileage has held steady since a slight increase after break in.

In both cases, your 12% would be roughly 2.2 to 2.5 miles to the gallon. Pretty sure the check engine light would come on long before it got to that point

What engine you running?

 

[jimmbo]

I see a slight bump running 93 octane (compression over 10:1) but gas mileage has held steady since a slight increase after break in.

Is that "Slight Bump" referring to more power? Even with a slight Increase in Fuel Economy with 93 Octane, the Cost per Mile is still higher than with 87 Octane

 

[dingbat]

Is that "Slight Bump" referring to more power? Even with a slight Increase in Fuel Economy with 93 Octane, the Cost per Mile is still higher than with 87 Octane

If I worried about fuel costs I certainly would not have bought either vehicle….lol

Both things are true actually
The mileage is pretty close, 1-1 1/2 mpg but the increase in HP is noticeable. Both vehicle get a 10%+ increase in HP if you go by factory spec

Worst part for me is the power band is between 80-90 mph. Great for running the long grades of the Allegheny but far too easy for “lead foot” me to get to triple digits