A friend I know owns a VW Scirocco TSi, he always puts Unleaded Optimax fuel in.
The TSi means Turbo Stratified injection. Any petrol car with a turbo should use the highest octane fuel available. Not a very good idea because petrol (where I'm from) is very expensive, especially the higher octanes.
You should use 95. Using anything lower should be for emergency top-ups i.e to get you to a garage that has 95. If you use a low octane fuel in a TSi you'll have a build up of Carbon in the engine, effectively giving you a crap mpg.
I've just got a 2.0 Diesel Peugeot 508 SW, it's great on fuel.
I wish I would have a diesel car but the only ones available here are either the Citroen C4 Picasso or Jeeps, which are quite expensive and not good on mileage since they're 3.7L at the very least.
I have turbo on my Audi, also made by Volkswagen, and I was told to use 91 and up. You should ask the dealership, they have to tell you.
Unfortunately, I cannot trust the dealerships here. The sales people just want to sell you the car so they can get a bonus in their paycheck, and they do not care about whatever happens afterwards. I know that from experience as well as because I have friends who work as salesmen in a couple of showrooms; however, none of them know about the fuel thing which is why I'm asking.
It's also in the manual. Car manufactures will recommend a certain octane. You can use a lower one however comma it will lead to pinging and less than optimal gas mileage.
I don't really care about the gas mileage that much since the two cars I've had were both 1.6 and not very gas efficient, at least when compared TSi engines' claims. To me it's really all about whether or not it will harm the engine and cause problems for it on the long-run. I mean I don't want to be driving around and then my car would suddenly stop and it turns out to be a dead engine, you know? A friend of mine told me that yes, the manual should say, but I don't know where to obtain that as the cars' vouchers don't say, but he also told me that it is usually written on the back of the car's injection door.
I found this post to be really helpful:
"95 RON in Egypt is roughly equivalent to 91 (R+M)/2 in the States, which is what the TSI engines call for as a minimum specification. Yes, the ECU will "adapt" to a lower fuel standard, but you risk a lot of stupid crap happening. Plus, when the ECU is retarding fuel mix and spark, your power and gas mileage will suffer. You also run the risk of knocking and premature detonation.
Newer DSG transmissions are nowhere near as problematic as the earlier ones, but they still have their niggling little issues. Best bet is to buy the manual.
Bottom line is run what your car calls for. Yeah, it costs more at the pump, but it'll run better for a lot longer and save you the headaches in the future."
So I 'm thinking I shouldn't bother, since 95 is actually the "minimum" specification, which won't even be as smooth as one would think.
