I recently (500 miles ago) changed to Mobil 1 fully syn(5w50). I notice after idling for a few mins (after driving) blue smoke from the exhaust, not alot but it is oil smoke.
Never needed oil between changes before, is this unusual?

Thanks in advance.

It's definately 5w50 (at a special price) maybe now I know why!
It was never going to be in there for too long anyway, I'll use it for now and change to a heavier brew. Although its been going well, I did a compression test, 2@170 + 2@180lbs. The head was revamped after a blown hose/overheat and I think they skimmed it so I hope the compression isn't too high.
Another worry!
Thanks for the opinions!

Are you sure is is 5W-50? The Mobil 1 I've seen is 15W-50.

Is there noticeable oil consumption? If so, then try changing the oil filter and topping off.

Changing to synthetic, or even another brand of non-synthetic, can loosen deposits and clean things up. Dirty oil doesn't seal as well as clean oil, so you might burn some initially. Unless you have existing bad seals or gaskets, consumption should settle down. I'd leave it in there at least a couple thousand more, topping off as needed.

Get thee to amsoil 15w/40 marine diesel synthetic.
It's got a good price and has a great anticorrosion package.

The 5w50 is simply too thin. It's thin base stock with VI improvers.

Hi dobiesan,

That's kind of wierd if it wasn't doing it before the synthetic switch. Maybe the 5 weight portion is too thin. I use Amsoil 10W40 in my 745T and it works great. My turbo is orignial (291K km > ~182K mi), but the engine only has a little over 30K km on it. Maybe the synthetic oil has illustrated some tired valve seals. Not usually a problem on B230FTs that I've seen though. Weird. I'd suggest trying a heavier weight like 15W50 Mobil 1 or 10W40 Amsoil or Redline. Mobil 1 is a fine oil and is better then non-synthetic, but I'd pick Amsoil or Redline over it any day.
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Chris. Halifax N.S. '91 745Ti, 291K km and '91 745 NA, 385K km.