Hella-Buggin'

I installed the third radiator because I was getting oil temps up to 250. I installed the third radiator and temps hover closer to 235 ish. Occasionally they'll spike up a bit after a hard long session but I'm always aware of where the temps are and will back off if needed.

stronbl

On hot days, air temp 90+ degF and track temp 100+ degF, I push close to 250 degF with 3rd radiator in my 997-2. Maybe a little higher when the track has many turns and short straights, for example Thunder Hill West in CA. So I can certainly see 250-260 degF without 3rd radiator if you are really pushing it. Also I assume you are reading the oil temp from the dash and not from the ECU. I have found my data logging is a few degrees less than what I seem to recall the dash gauge shows (no digital readout in 997-2). Also do a Blackstone analysis a couple times per track season and so far no worries at all - additives and all remain stable.

From my experience, the oil temps you report are high but not unexpected and I don't think dangerously high.

No help on the white smoke issue.

M3 Defector

Third rad won't drop your oil temps that much. I have it and run around 245 on the track almost no matter what temp it is outside. Before the third radiator it would get up to 250.