My car came with 20w-50 non-synthetic oil. What will happen if I use 15W-50 synthetic oil to top up? The reason I want to do that is because all synthetic oil I've seen is 15W-50 or others, but not in 20W-50. Please help. Thanks.

Just top it off with what is in it and switch at the next oil change. I do not believe it will harm anything though. Most synthetics say it is ok to mix right on the bottle.

FYI, oil, fuel and lubricants are completely compatible as the US Military required this way back in WWII to prevent problems. Of course you can't mix white grease with molybenum, etc. But you certainly can mix different manufacturer's same white grease, etc.<br>

I wouldn't choose to mix syn with dino just because the synthetic is much more expensive (unless you already have an unlimited supply). Pick up a quart of 20/50 at your local store and use that to bring up the level.<p>BTW, Amsoil makes synthetic in 20/50 in two different grades (racing and something else...I forget). I have run it in my past several cars and it has all of the same benefits of the biggies. I'm waiting for the 12,000 mi mark on the A4 1.8T before I switch. Check your phone book under lubricants for a local dealer. Nope, I don't sell Amsoil, just have used it for a long time.<p>Best Regards,<br>Steve

There is always much talk of reliability on this forum. While it is hard<br> to say exactly how reliable the a4 is, it seems safe to say that is less reliable than<br> almost all of the major Japanese brands (especially lexus). Why is it so hard for<br> the Germans to build cars as reliable as Japanese models. The country where the cars are built<br> doesn't seem to make much of a difference since Honda and Toyota build reliable cars in the U.S.<br> The Japanese have been building more reliable cars for years, so their methods aren't a big<br> secret. Sometimes, people use the excuse that European cars are more "innovative" and<br> more on the cutting-edge of technology. But they both have things like ABS, xenon healight,s<br> sunroofs, traction control, turbos, multi-valve engines, electronic transmissions and engines,<br> and on and on. In some cases, the Japanese have been more innovative. In fact, German cars generally have less features than Japanese cars<br> at a given price range. So, why for example, do Audis still have more electrical problems (sunroof switches, door locks, headlights are not<br> is not cutting-egden more mechanical problems (things like synchros and wastegates are hardly<br> new technology). I could forgive first-year model teething problems (even though Japanese makes tend not<br> to have these problems), but it seems like Audi still makes the same mistakes year after year,<br> model after model. I'm equally amazed that the Japanese can't make a car that<br> drives as well as German cars. But, that could be seen as more a concious engineering<br> decision. Choosing poor quality, I hope, is not. I'm just frustrated b/c, as much as I want<br> an A4, its hard for me to spend so much money on a product that is so faulty compared with<br> others in the same price range. But in the end, I know I will :).