I don't think that the oil change has been the reason for the rise of the consumption figures. Usually the consumption figures tend to drop a little as the vehicle ages. Has your garage analysed your engine management system data?

Furthermore, experts do not advise changing the brand and/or type of the oil used because of (a one in a million) chemical reaction risk. Don't cause any damage to your engine while trying to cut down on gasoline expenditure ;)

ravenx
'00 Black S3

Hi Ravenx,

I did take it to the dealers soon after it's 10000 mile oil change, and they supposedly checked the engine over etc., but you guessed it, they said nothing was wrong.

I understand what you are saying regarding fuel consumption and age. But at 15000 miles, I would have thought that the car would be loosening up quite nicely, and better fuel economy would result. Not go down. (?)

What it boils down to is: I was getting the same performance, but better fuel economy on the factory "fitted" oil, than what I'm getting off the stuff the dealer put in. What the dealer put in - I do not know, but its coming out! :)

I think I understand what you are saying about engine damage. To thin or thick, and it could damage the engine. Yes ?

Thanks,

Alan
'99.5 A3 1.8T MS Silver

I tried to say, that usually 15000km old cars have better fuel economy than 5000km old cars.

Although I am not a chemical expert, I have read and heard from several sources, that an oil from another manufacturer (e.g. Mobil) can chemically react with the leftovers of the previous oil (e.g. Valvoline), which had a different chemical formula than the previous one. Though the chances are small, such a reation might cause performance problems.

The dealer has changed your oil from the factory "fitted" one with an "x" brand. Now, if you change the "x" brand with a "y" brand, you increase the chances of such a chemical reaction to happen.

Therefore, before putting the blame on the oil, other sources likely to cause such a problem (ranges from the ECU to the air filter) must be tested to avoid an extra oil change.

Regards,

ravenx
'00 Black S3

So you recommend an engine flush before changing the oil? Thats sensible advice.

What oil do you intend to put in your S3?

Alan
'99.5 A3 1.8T MS Silver

Well, as I said before, I am not a chemical expert. Therefore I can't recommend an engine flush (I'm not even sure that such a thing advisable and won't cause any damage)

I expect no oil change before December 2000, but I would first ask the dealer what brand they use. Then I'd e-mail Audi and ask them what brand is the factory "fitted" oil (I don't expect them to answer my e-mail, but I would send it anyway). Then I would either go on with the dealer's recommendation or ask an independent expert. We have a very good tuning specialist here and I am going to forward your problem to him and try to get his opinion. I'll get back to you if he makes a noticable comment.

Regards,

ravenx
'00 Black S3

But, I'm getting the oil change done this weekend. And I think I'm going to choose the Mobil 1 0w40.

I e-mailed Mobil again today with some of the concerns and issues raised in the posts in the performance forum. They were adamant that the 0w40 exceeds the requirements of VW500, and is highly suitable for performance turbocharged cars.

I know they are "selling" it to me/consumers, so they probably would push it a little. But the way I see it, if 5w40 is the Audi recommended thickness of oil, 0w40 is just going to mean it's even better in winter, it's still got the 40 SAE rating at higher temps.

Anyway you must be sick of talking with me over this buy now, so I'll shut up.

Thanks for your input, as always.

Alan :)
'99.5 A3 1.8T MS Silver

All,

I know it is probably a little early to start to comment on the effects of the Mobil 1 0w40 that I have just put in my car BUT...

The car does seem to rev smoother and it sounds a bit smoother too.

I can't comment yet on whether performance/economy has been improved or not, because I'm "mid-tank" at the mo. But it won't be long before I have some figures for you.

On a related matter. I can confirm that my dealer does use Castrol semi-synthetic oil (Syntec) 10w30. So that is the stuff I've just taken out.

I'll keep you posted.

Regards,

Alan
'99.5 A3 1.8T MS Silver