Dash01

This just came on with the last drive, after I topped of the expansion tank with distilled water.

Prime suspects?

MAGK944

Oil in coolant usually means your oil cooler seals have failed.

Dash01

Thanks, that's pretty much what I thought, but want others more knowledgeable to chime in here in case there are other prime suspects such as head gasket failure which would explain oil in coolant but no coolant in oil. I'm due for a heater control valve replacement, but that involves only the coolant system, with no oil mix potential.

MAGK944

If you don’t have any other symptoms and there’s no coolant in your oil then it’s almost certainly the oil coolant seals and not the head gasket. Coolant in oil, misfiring and white smoke out the tailpipe are usually signs of a head gasket failure on one of the coolant channels. Coolant in oil means you’re also doing your rod bearings.

Report back with what you find when you open up the oil cooler.

Dash01

OK, thanks.

Follow up questions: This is an '86 Turbo, which I gather has the early type housing and Oil Pressure Relief Valve, so I need the early version seal kit, for about $35.

Any particular brand or source to get, or to avoid?

Is it really necessary to replace the been-working-fine-or-30-years OPRV, or just use a new O ring?

Is it worth removing the exhaust manifold (perhaps risking stripping a stud, etc.), or (with the belly pans already off the car) just bust knuckles working under a raised car?

black944 turbo

I agree with Magk 100%. I had this issue with mine about 10 years ago. I have not had any "milkshake" since the repair was done. Good luck.

I can't comment on your other question because I paid a shop to do mine (had a drive planned for a few days after the failure occurred).

TurboPropRob

I had same issue in my N/A. Oil cooler seals were the problem. Did the job myself. Messy but worth it.

Rob