For your T6 I would say without a doubt synthetic. Our T6 has had Mobil 1 synthetic from 7500 miles onward (oil changed every 7500 miles). Even at 54,000 miles the oil on the dipstick is still pretty clear and shiny.
Some advantages of synthetic are:<br>-better protection at high temps (due to better shear stability and temp stability)<br>-helps prevent cokeing on the inside of your turbo - does not breakdown very easily at higher temps<br>-better wear protection<br>-better reduction of friction ( results in better gas mileage )<p>Note - if you have a turbo engine non-synthetic is not adequate protection. The factory fill is a synthetic blend.<p>Mobile 1 is good from price/performance perspective and easy availability. AMSoil is the best wear/protection/quality wise. I have used AMSoil in my engine (2.5T) since the 1st oil change and the gas mileage is excellent.<p>Best to steer away from semi synthetics. 1/2 of what is on the market claiming to be "synthetic" on the label is not a true synthetic (semi-synth, etc).<br><BR><BR>
<i>Modified by ss60 at 9:02 AM 6-13-2006</i>
<br>Where do you get your information that Amsoil is the best? Please reply with only independant tests, not from the Amsoil site.<p>Synth (real synth) will do all of the above. One very important thing with synth is that it will give very good top cylinder lubrication because it doesnt burn away by the heat of the engine. When rebuilding a engine, the most wear is at the top of the stroke where the traditional oils have a hard time lubricating. The synth oil stays there and thus lubricates and helps to keep the rings sealed. This also<br>helps with the reduction of contaminates getting into the oil.<p>Dont be fooled by the advertisers that claim that the oil lasts 50K miles and you can extend the the<br>oil changes to some huge number. Problem with this is that the oil may last, but it will be so contaminated that regular oil and regular changes would be better. The oil lasts, but the filter<br>cant keep it clean. The only way to extend the changes is to add a bypass filter that filters just a<br>trickle of oil, and cleand the contaminates almost completely.<p>Only way to really tell if the oil needs to be changed to to have it tested. This will also tell if<br>there are wear issues. Color, or the lack of is not a good indicator.<p>Synth is great, but nothing beats just regular oil changes with what quality oil you choose. Doing this<br>will get you several hundred thousand miles of engine life. Synth will just get you some more if <br>changed when it is needed.<p>
This is one of the better websites I've seen regarding dino and synthetic oil. I stumbled onto it about 3 years ago. There are some dino oils that perform as well as some synthetics (not as well as say Mobil 1 or Amsoil, but perform very well nonetheless). Then there are some synthetics and blends that perform worse than dino oils.<p><A HREF="http://www.themotoroilsite.com/forums/index.php?s=8786926183ba506ee6ad9908a8108e97" TARGET="_blank">http://www.themotoroilsite.com...08e97</A><p>This site has an exhaustive, comprehensive list of most all the available dino and synth oils on the market and their respective test ratings.<p>Interesting site for sure.
I don't know what type Volvo recommends but our dealer uses Castrol Syntec which, from what I researched is not really a Synthetic oil like Mobil 1. Thats why I give my dealer Mobil 1 at every oil service.