Yep fully agree with cooper man re the mineral oil. These are modern engines and fully synthetic is the way to go here!

4w-40 well I have no knowledge of that as a grade... So let's look at 5w-30 and 5w-40. First number is a winter rating or a cold rating temperature and the second number is for hot temperatures. Basic advice is don't mess with the first rating or W number. This is the lightest oil viscosity your engine can maintain mechanical separation, ie. prevent metal to metal wear contact.
Now to the second number. Ford would have a small turbo in most of these engines and would run as standard 5W-30 in order to successfully lube the turbo, Well there's more to it than just that, and it's all a compromise! So how hard do you drive your car? If you race it and always run hot I'd suggest you use 5W-40 as this second grade will give you greater component separation when hot over the 30 grade. The oil manufacturers would tell you this.... In Europe where temperatures rarely exceed 30'c 5w-30 would be the oil of choice in hotter climes use 5W-40. So generally for the cooking version of your engine 5W-30 is fine but you probably will run hot from time to time and you have no turbo to consider with small oil ways so I would go with 5W-40 and in fact I do.... it will protect your engine more! The next thing is to change your oil way sooner than any car manufacturer would suggest.... it is the cheapest repair bill you will have! When I hear you ask! Well again it depends on use... track your car, come home and change your oil.... use it hard on the roads and start thinking 3500 mls, no more than 5000 mls and if you don't exceed that annually then change it once a year, at the end of the season rather than at the beginning so nothing toxic sits in there over winter! And please... don't believe those who tell you that at low mileages you don't need to change the filter every year! Yes you do! Never use a cheap filter they are not the same. Fortunately, Fomoco are excellent quality and K+N are good too! and what's a tenner to protect your engine?

I use a millers product, It's 5W 40 CFS nano ++. It's the best oil at the best price you will find, all the racing boys use it And I can assure you, you will notice a real difference! People will tell you that 5W-30 offers less resistance within the engine and you will feel that in acceleration.... total tosh and a performance oil like I have suggested with nano technology is way superior.


A note of caution here for those running older cars with say TR tech engines or older. You really are better sticking with a traditional 20/50 oil being semi synthetic or fully synthetic as they are designed to clean older engines and keep them clean. They will never have an oil change limit of more than 5000 mls or generally 6 months in time.