I recently purchased a Fiesta 1.6,16v si. 94/95 M reg.
I believe it is a series 2 Zetec engine.
The previous owner (fathers neighbour)works for Fords and used a 10w40 mineral engine oil and insists this is the correct grade and not to alter it or use semi synths.
My research shows that 5w30,5w40,10w40 & 10w30 are compatible oils.
Am told that 10w40 can cause tappet problems over time.
Castrol tech support advised 10w40 and that a 5w30 may not offer suitable protection in the extreme high tempatures of an engine.
In this case a 5w40 would be a better option,better for cold starts and offering greater protection at high tempatures but I think about the tappets problem.
Having read here most/all of you use a 5w30 viscosity oil,do you think the older engine needs a higher viscosity oil such as a 10w40,5w40?
Haynes auto manual suggests 5w50 through to 10w30.
A 5w30 will offer equal protection when hot as a 10w30 and better when cold starting.
The engine milage is some 52000 only.
Whats my dream oil please?
Have emailed Fords for advice as well.
Obviously I want to use the correct viscosity oils but have had so much conflicting info its difficult to fathom