Fuel additives

[nermal]

Does anyone use fuel additives (eg. octane booster). Are these good or bad for your engine? which brand(s) do you use or recommend?

VW will sometimes provide fuel additives (valve lubricant IIRC) when you pick your car up from a service.

- thinking there should be some general EA888 place for this kind of question

[Lucas_R]

In my experience octane boosters are a total waste of money. Most are $25-30 for a small bottle and you don't notice any effect. A cheaper alternative to achieve the same thing would be to pull into a United petrol station and put in 5-10L of E85 to mix in with your tank of 98 octane.

[petemac110]

I throw a bottle of Redline SI-1 fuel system cleaner in the tank before just prior to changing the oil. The SI-1 is a high PEA formula which is apparently what you want to look for when choosing such a cleaner.

My MY18 Passat 206TSI has both direct and port injection so is somewhat less prone to carbon build-up to begin with, but I figured throwing in this additive every now and then wouldn't hurt.

Does it really do anything? I don't know... I have no scientific evidence nor any real empirical evidence. I wasn't expecting the engine to feel any different, and any reductions in carbon build-up would need a physical inspection or borescope to verify.

I'll tell you what though, adding a small amount of this to my lawnmower and whipper snipper engines certainly perked them up! It was worth purchasing for the SI-1 for that alone!

[Sharkie]

A number of years ago now (probably 10 years), we actually dyno tested the effect of octane boosters on a tuned GTI .... and yes, you will make more power using it. Not a massive amount (up to 5kw and up to 10NM) but still an increase. The VCDS logs certainly showed the car knew it had higher octane fuel in that it pulled less timing on the boosted fuel.

I occasionally (probably once a year) put a bottle with cleaner and octane booster in, although this is more for cleaning purposes than anything else. Not worth the extra $$ to use it often IMO.

[nermal]

I'll tell you what though, adding a small amount of this to my lawnmower and whipper snipper engines certainly perked them up! It was worth purchasing for the SI-1 for that alone!

Heh, I once bought a drum of toluene for my first car (VK Commodore) as an octane booster. It seemed to make a little difference, but may have been a placebo.

My Dad started putting it in the lawnmower and man did it rev hard... lawnmower didn't last that much longer after he started running it on toluene.

That was probably the last time I used an octane booster.