WHAT’S THE RIGHT OIL?
QOur 2007 canal boat has a Nanni three-cylinder engine. It has covered 1,300 hours, mostly canal cruising. The engine only idles when used in a lock. We seldom run to just charge batteries. I have used the 15W40 API CD-rated oil from new but have a chance to buy 20 litres of Mannol API CF 15W40. Is this likely to be too higher a spec for a 1,300hr engine? WIRREN, via the CB website
ATONY REPLIES: The first question is what do Nanni say? You should go by the manufacturer’s recommendations. The last time I looked on the API website it said that grade was obsolete and superseded, but canal use is highly unusual in that our engines rarely have to produce much more than a few horsepower. Diesels tend to prefer working under a reasonable and varying load, so a lower grade oil is often advised. Yours is a three-cylinder so of more modest power than many, this means it will be working harder than the larger engines.