I have a 98 Expedition with the 4.6. It has 56K on it. I just did an oil change from regular to Mobil 1 synthetic 5W30. Now at start up it puffs a little smoke which it did not do prior to the swap to synthetic. Does anyone know what causes this and should I be concerned? Thanks in advance.

 

That sounds a little strange. Maybe since the synthetic is slicker and composed of smaller particles it could slip past your rings causing the engine to burn oil. Keep an eye on the dipstick. If your losing oil go back to regular oil or switch to a heaviers synthetic like 10w-30.

-Jon