E36 M3 Evo oil cooling

[andygtt]

I took my std M3 evo on track recently and it behaved impeciably with the exception that the oil temperature.

A friend has said that this is comon and thus I figure the guys who regularly track theirs must put a cooler on it so was wondering what people have done and how just so I can get ideas before I start buying parts.

any pics or advice would be appreciated