Shake Your Carbon Off Baby

[Lalo]

Morning all,

My car is being serviced right now (15000 km service), but I got a call from the technician telling me that they need to de-carbonate my car to get rid of some carbon deposits that are caused by bad petrol, which made the car shudder on some occasions. Cost is $220. The problem is that I've only used one brand of 98 RON fuel since new, thinking that it will keep the system happy forever. Anyone had any similar experiences? What do other people use for juice?

Cheers

[DANSLEX]

Strange. I use 98 RON fuel all the time, and don't have any problems. Perhaps at some point in time you unknowingly got some bad fuel somewhere?

[FrankyX]

Sounds like a standard mechanic's trick to me. De-carbonate, are they serious. The car is still new, I'd be very hesitant on paying that. Is it being serviced by Newcastle? They've had some pretty bad wraps in the past.

[Sapphire Cam]

Had a fuel injection service as an add-on to my 45k service. Made a big difference (I set up a post here somewhere about it). Was a $50 add-on. They disassemble parts of the fuel system for a chemical flush and physical clean. Made notable difference to acceleration and a moderate improvement to fuel economy. I only ensure I get 95 or 98 RON from the big distributors (Shell BP, Caltex, Mobil). Regardless, over time your fuel system will still clog up a little bit. The very nature of the IS250 injection system I understand is that it is a little more sensitive to the issue than say your average Falcon or Commodore.

However, Im surprised they are suggesting this to you after 15k. Not required I wouldn't think. And that cost seems extravagant. Normally a Lexus fuel system service retails for about $110-120, but my dealer throws it in for an extra $50-60 on a service if you like.

Incidentally my friend got his 2003 C-class serviced the other day.... $900 plus $104 for two wiper blades!!!

[Lalo]

I already approved the job, as the technician said that it's the only way to fix the shudder problem. He said that the deposits come from bad batches of fuel, which are not particularly associated with a certain brand. I've always used Shell's V-power.

The dealer is in the Sydney metro area (I think this narrows it down to 4 only!).

Cheers

[IronFist]

I wonder if the carbon is the result of using 98 RON fuel?

I've notice that ever since new my tail pipes are thick and black compared to other cars I've had in the past?

[last1]

Higher RON fuel requires a cocktail of ingredients to ensure the fuel meets the "98" standard and often involves using more carbon rich ingredients (say octanes, which have 8 carbon atoms in their chain). The actual composition of the fuel depends upon the given refinery/ingredients on hand/exact composition of the crude oil delivered. When a carbon rich fuel (denser also!) is produced the refinery will generally add more/better detergents to clean out carbon deposits from the engine (which is why the industry was pushing the line "with extra engine cleaning detergents" when 98 fuel was first released) - sending them through to your exhaust.

It appears that the detergents added to some batches are not up to the job!

[IronFist]

So does that mean the carbon deposits are carried out through the exhaust rather than inside the cylinders?

I've been only using Mobil brand of 98 RON

[last1]

Normally, carbon is burnt during combustion and passes out the car's "rear end" as carbon dioxide. Seeing these exhaust gasses are rich in carbon (which may include some carbon which is not totally burnt) they leave deposits on everything they touch (hence the black inside your tail pipes). Unlike the carbon built up inside the cylinder which can usually be removed by re-combusting it (pedel-to-the-metal does a great job! You can also add some products into the fuel which will encourage the carbon to burn), there is nothing to clean out the tail pipe.

Personally, I like my tail pipes black, not grey - and I like the chrome tips shiny! :D

[akuma]

Comes to think about it my car produces large amount of white smoke when i first start up my car, for about 5 - 10 mins, is that normal? That's how it was when i first got the car, and now it has done 22k but still the same.

[Atlantis]

Mostly likely steam from condensation build-up in the exhaust system. Nearly all cars do it.

[Lalo]

I did send a enquiry to Shell through their website; still waiting for a reply though. Seems like I need a good old fashioned letter!