yesterday i went out to buy some service parts for my car. now the book says that i should use 10/40w and bear in mind that this is a turbo diesel ford escort. i went out and bought 15/40w instead of 10/40w and im worried that the 15/40w might mess the engine up. it was the only one in the shop but is meant ford diesels with turbos. will it damage the engine if i use the 15/40w inside of the 10/40w?

thanks for your help everyone.

It should be fine mate. I used to use Castrol GTD in my TD all the time. Bit more expensive but a very good quality oil.