My T4 1991 2.4 westfalia (150k) is burning way too much oil. must have put 1 litre per 100 miles in. it also losses a bit of water. not losing any power but when under stress blows out plenty black smoke and smells a bit. has whitey grey smoke when first starts but no signs of oil or water loss from engine. help : }= thought it may be possible head gaskit, any suggestions.