Hello everyone, we all know that the most expensive oil isn't always the best and especially not for classic cars. So, just which oil is the most suitable for the older Z cars. I know there was an article in a recent/current Practical Classics issue but was interested in what everyone was using and if anyone had any horror stories with "the wrong oil" I'll start with a story, in the army we use an engine oil called OMD90. It is a good oil and it contains a small amount of some sort of detergent. My friend at work has a triumph TR4a on its second engine now because of "the wrong oil". So from this I am keen to use the most suitable oil for the 70's mechanics in the old Z. Any help and fact and opinions are welcomed!! Thanks for everyones time. Matt