Many thanks for the reply, it was probably a bit of a silly question! I vaguely remember reading something years ago (no doubt an oil company booklet) saying that synthetic oil shouldn't be used after 5 years but you are right, the age shouldn't make any difference so I'll add it tonight!

According to the "OIL BIBLE".....Synthetic oil can be used no matter how old it is, its a differant matter for mineral oil, dont use it if its over 20 years of age. During the Eighties a lot of cars had their oil turning to sludge, the finger was pointed at the oil companies who changed the formulation and blending techniques which led to the development of better mineral oils and the introduction of Semi- Synthetic and fully synthetic oils, this solved the problem through to recent years where the problem has again reared its ugly head, sludging is on the increase again because oil is being overworked because car manufacturers are fitting small 4 ltr capacity sumps to engines were 10 years ago a 5 ltr sump was commonplace. Oil is overworked in these modern turbo engines with small sumps so changing ahead of manufacturers specs is best.

Edited by barkas on 25/06/2010 at 01:46