Right, had an Oil Cooler fitted last week by Nick at HillPower.
I got a sandwich plate with a built in 80 degree stat.
Nick said it was running about 90 degrees on the m/way, and fair enough on the way home, it was running about 80-85.
The problem is now, after a couple of days, the oil is taking ages to warm up, and only gets to about 60 degrees.
The only thing I can think of, is that the stat had stuck open.
I bought it from Demon Tweeks, and will be there on Wednesday morning, so I need to figure out if its dodgy stat, and get them to replace it if it is.