What, if any, problems might be caused by going back to conventional oil after synthetic? The previous owner of my 'new' A4 2.8 put synthetic in at ~4600 km. The car now has about 13,500 km on it.

I am slightly concerned that the engine may not have had a sufficient time to 'wear in' on the original factory oil fill and thought that maybe going back to conventional oil for a while might help to complete the 'wear in' process.

Opinions? Hard data?

Continue using synthetic. Break in period isn't really an issue....LOTS of manufactures use synthetic right from the factory in fresh engines. Going back isn't going to do anything and I think that the original oil was in there long enough for 'proper break-in' to have occured.

But I'd agree with Nick. 3000 miles seems plenty for any break in. No harm switching, though, if you want. At 9000 miles, the engine is still like new. I'd just drive the car hard and have fun.

But why do you suspect inadequate break in? Any reason in particular? Unless you have oil consumption or low compression, I wouldn't even consider the possibility.

There are an increasing number of engines coming right from the factory with synthetic oil. BMW 3-series is one of them. BMW now requires synthetic for all subsequent changes also (warranty). There are quite a few other manufacturers doing this also, and I suspect Audi will join them in a few years. Engines will break in just fine with synthetic oil. People seem to think that it is incredibly "slippery" but there's not all that much difference in that respect from good conventional oils (e.g., Fuel conserving II rated). Synthetic has other advantages such as resistance to heat and a long life without breakdown, however. (Especially important for those with the 1.8 Turbo engine).

Just keep changing with synthetic. However, the reality of the situation is that you can use conventional oil without any problems. Just change it every 3000 miles or so. (You can easily go longer w/synthetic if you want - BMW's average required change interval is now about 15,000 w/synthetic, although I personally wouldn't go that long.)

>There are an increasing number of engines coming right from the factory with synthetic oil.
>BMW 3-series is one of them. BMW now requires synthetic for all subsequent changes
>also (warranty). There are quite a few other manufacturers doing this also, and I suspect
>Audi will join them in a few years.

I am aware of this trend.

>Engines will break in just fine with synthetic oil. People
>seem to think that it is incredibly "slippery" but there's not all that much difference in that
>respect from good conventional oils (e.g., Fuel conserving II rated). Synthetic has other
> advantages such as resistance to heat and a long life without breakdown, however.
>(Especially important for those with the 1.8 Turbo engine).

I am also aware of the synthetic advantages, but have read some anecdotal 'evidence' (A4 Forum? &/or quattro-list archives?, can't remember now) that the factory fill had something extra in it to promote proper 'bedding-in' of engine components. Any way, there was some indication that people who first changed oil after only a 1,000 or so miles had engine problems later on. Mostly excessive oil consumption and low power IFIRC.

> Just keep changing with synthetic. However, the reality of the situation is that you can use
>conventional oil without any problems. Just change it every 3000 miles or so. (You can
>easily go longer w/synthetic if you want - BMW's average required change interval is now
>about 15,000 w/synthetic, although I personally wouldn't go that long.)

Hmmm.... my maintenance manual recommends oil changes every 12,000 km (7500 miles), I assume with conventional oil, since that is what the Audi dealer will put in as part of the 'free' Audi maintenance servicing for the Warranty period. Of course, the other part to this is the fact that I will have to supply my own synthetic oil, or get truly gouged by the dealer if I request a synthetic change.

Thanks for the help.

>But I'd agree with Nick. 3000 miles seems plenty for any break in. No harm switching,
>though, if you want. At 9000 miles, the engine is still like new. I'd just drive the car hard and
>have fun.

That is happening, although I haven't really been driving 'hard' yet, unless you classify 2200 km in three days of highway driving 'hard' ;-). Still have to feel my way around to determine the car's limits.

> But why do you suspect inadequate break in? Any reason in particular? Unless you have oil
>consumption or low compression, I wouldn't even consider the possibility.

I have no reason to suspect inadequate break-in, the engine had plenty of power to pass anything on the highway, even though the car was pretty heavily loaded with four winter tires on
steel wheels and our luggage plus a few purchases ;-) Also, no detectable oil consumption. If the consensus was that the first change was too eartly, I just wanted to be able to possibly do something while the engine is still relatively 'new'. As I mentioned in my other reply to RTM, there was some concern about too early a first change causing engine problems later in life.