I definitely plan to switch to Mobil 1 synthetic, but haven't decided when to make the switch. I know this whole "oil change" thing is such a big, controversial issue and I've decided to have mine changed every 5K(1.8T), but to switch to synthetic. Is the engine sufficiently broken in enough at 5K to switch to Mobil 1 or should I wait til' 10K? What was your experience? <p>JT 99' 1.8Tqms

I would start now cause if you delay all the components tend to rely on that thick petrol based oil. Synthetic is smoother and thinner than conventional oil. if you wait too long when you do switch to synthetic it would be too late. i have a 89 mercedes benz 2.6 i broke in the car for 1,000 miles then i switched to synthetic. ever since then i ran Mobil 1 15W/50 and now the engin runs true and strong. occasinaly the dealer slips in that cheap "O" MB oil and you can tell a diffrence!<p>In my Audi i did an oil change at 1,500 miles with synthetic oil i did not wait for the 5,000 mile service. my car is due for the 10,000 mile service now so.....<p>BTW tried Prolong on my Mercedes and there is a big diffrence in smoothness! a 11 year old car now runs smoother than ever! i am going to use prolong on my audi in the up comming service<p>JC M. 1.8TQMS (Abt II, Oettinger, Bil/H&R Race)

I hate to be the one throwing cold water but my mechanic who services my Porsche feels , as long as you change oil on a regular basis, as specified by the munufacturer, synthetics are a waste of money. He uses synthetic oil on only thise cars that come with synthetic from the factory such as the newer Porsches. Also Audi does not recommend synthetic oil although they say it will not harm the engine. Personaly I would like to use synthetic but I hate to do so when knowageable folks belive I am just throwing away my money.

I switched my 1.8t to Mobil 1 15W-50 at my 5K service, and have had no problems. No oil leaks, no oil usage, just a smoother running, quieter, freer revving engine that also cranks over much easier during freezing weather. Add in the extra protection Mobil 1 provides against the severe Texas heat, and it is well worth the extra $12 or so at each service.<p>Dave M - 97 1.8tm (synthetic fan for life)

I will wait till 10K miles, I think MOBIL makes this recommendation too, just to be safe. I think in a non-turbo engine, changeing conventional oil often (3K) is almost as good as synthetic, but I think there is a strong case for using synthetic oil in a turbo engine, to protect the turbo bearings from hot-soak coking problems. The oxidation temp of synth oil is much higher, extending turbo life.