Just to build on this, I was wondering how you modify the grade of oil to accommodate any changes in engine specification.

For example, I have always run my Cosworth on Magnatec Grade 10W40, which I think is a synthetic blend oil. The principal reason for this is that the chap who built my engine told me to!

I have on several occasions suggested to him that perhaps a fully synthetic and thinner grade oil may be more appropriate, which he has always been firmly against.

What would your thoughts be on oil grade : performance alterations? Is there any set guidance that can be followed?

Very interesting read though

JJ