kosmo

the vw/audi and bmw guys recommend it. I dont know whats P's official position is.

LlBr

I remember a firm advisory by Porsche...... something like, "do not use fuel additives." I think it was in the manual.

swajames

In some parts of the world, perhaps those with more variable fuel quality, Porsche actually recommend it...

alexb76

I think that's for oil additives. I've never seen one for fuel additive.

My dealer actually said that during oil service, they also do a fuel injection cleaning (additive).

Fin Fever

I usually fill the car with 100 octane from a local (specialty) fuel station (76) I only put the 91 octane in if I have to (running low and no good gas within range). I wonder if the 100 octane has techron (or similar in it) any thoughts? should I additionally add techron periodically.

LlBr

I thought I was going nuts for a minute! Sorry Guys.

I Just checked the 997/S manual: nothing advising against using additives.

Then I checked the 997TT manual and there IS an advisory against using additives:

WTF? Heck. Just do what you want with Techron I guess. However Just say "no" to nitro.

Carrera Mike

little percentage of it sip through your piston rings/dilutes into your oil/lube system, which degrades oil lubrication properties. thats why pro advices before oil change.

ADias

Techron is a Chevron brand. 76 is also a top tier brand and their 100 gas may have their PROclean additive.

You are wasting your money filling up with 100 gas. To get a 93 blend (the correct octane for our cars) you need 4 gallons of 100 and 12 gallons of 91 for a 16 gallon tank.

Macster

Do not know if Techron in 100 octane gas. You'll have to contact the gasoline company and see if you can learn if it has the additive or not.

Whether it does not doesn't, you're wasting your money. Switch to using a top tier gas -- premium grade -- and bought from a busy station, saving the racing gas for well racing.

Sure, the premium gas available in CA has less octane than Porsche recommends -- by one or two octane points -- but the difference in what you're paying for 100 octane gas is costing you way more money in higher fuel cost for that one or two point octane gain. Any octane over the engine's stated octane requirements is just wasted octane.

(Some engines can have their octane requirement go up with miles as carbon and other stuff builds upon combustion surfaces but using a good gasoline should see this build up reduced or even eliminated after some miles.)

You can hurry the process up by just before next oil change using a bottle even two of Techron according to directions then after oil change switching from using race gas all the time to a quality premium non race gas.

Of course, when (if) you track the car use race gas.

Sincerely,

Macster.

YA911Fan

I don't see how a fuel additive could help clean the valves in that case because the fuel is injected directly into the cylinders, bypassing the valves...

Fin Fever

thanks for the advice, I will go with the blend to save some $$$

LlBr

Baked on lubrication oil? I dunno. Just a guess. Probably wrong.

Macster

The new DFI engines are designed (along with the previous conventional engines) to have some back flow of exhaust gases into the intake system to pollute the incoming air and lower combustion effiiciency and thus combustion temperature and lower NoX production.

Primarily this is how the deposits form on the intake valves in the first place.
The second source of intake valve deposists are from the crankcase fumes routed from the engine crankcase by the AOS into the intake manifold. Keeping the oil level below max. can help keep the oil vapor content of these fumes lower -- the AOS is not 100% effective at removing all oil vapor from the crankcase fumes before routing the fumes to the intake manifold -- and thus intake valve buildup down.

Anyhow, as a result a fuel additive can reach the intake valves in vapor form -- maybe even liquid form shortly after a cold engine start -- and upon reaching the valves condense into liquid form cause the intake valves are of course cooler.

In either vapor or liquid form the fuel additive if it had any detergent aspect could help keep the intake valves clean.

Sincerely,

Macster.

YA911Fan

That's the part I don't understand. I'm assuming the fuel injection takes place after the intake valves are closed and whatever fuel additive was injected gets combusted in the power stroke (I'm also assuming the additive is more volatile than the fuel itself).

Apparently one or more of my assumptions is faulty!

944CS

I remember reading a Porsche document stating Techron was the only fuel additive Porsche recommended. This was years ago however