AH HA! i think you've just nailed it for me oldcorollas, This cressida hasn't been driven all that much, it's done maybe a total of 5000k's in the past 2 years!!. Mostly short 15-30min drives 3-5 days per week and maybe 1 or two long drives within that 5000'kms.
So I'd say that's the cuase!
I'll suggest he change his oil and take more long drives (the nerd needs to get out more anyway)