Have been looking at a product called Metabond on ebay. £35-00 for a small tin. Supposed to reduce wear, increase power and also reduce engine noise. Very tempted but would ask if anyone has used it or has experience of engine oil additives in diesel engines , whatever they say the benefits are there must be a downside, or am I just being overly pessimistic. My engine is less than a year old and has only 4000 on the clock