Originally posted by Kremithefrog: Ford recommends using 5w-30. On newer vehicles 10w-30 would only be needed in a desert. And if you run a true synthetic (mobil1, amsoil,etc. not castrol) 5w-30 you can run it all year in just about any climate. 10w-30 can mess up the VCT system for ya'll that are unfortunate enough to have it, for us pre98ers, I'm not sure what it can mess up, but when I started using mobil1 the engine ran a bit better.
i use castrol SYNTHETIC...says it right on the bottle! not SYNTECH...Synthetic.
from castrol web page Castrol Formula SLX is a world beating lubricant for drivers seeking the very best performance from their car. It's the first of its kind, providing a fully synthetic, ultra free flowing premium performance OW-30 engine oil that gives instant lubrication and superior, low-temperature protection.
