Oil in coolant - thinking it's the oil cooler, opinions?
 

Cliff notes, 02 R53 ~93k miles

Originally oil in coolant was caused by blown head gasket from a faulty low speed fan. Gasket was replaced a few months ago. Car was drivable for about 3 weeks and was fine until car almost overheated and high speed fan came on at a mini event.

Checked the car at the event, and saw oil in coolant, that overflowed and low levels of oil on dipstick. Car has been sitting for 2 months so far.

Just checked the car's compression worried that there might be engine damage (gasket, block, head etc) but compression came back well - 155, 150, 150, 160.

Only other thing I assume it could be is a fault oil cooler? Just looking for the community to chime in in case I've missed anything.

TIA.

The gasket can go bad in different places. If it is just between a oil channel and a coolent channel, compression won't be effected.

I can't answer about an oil cooler issue.

Did they use an OEM replacement gasket, MINI makes two kinds depending on what they did....sometimes they machine the head to the next manufacturer dimentions in order to remove any defects or warping.

FYI - Most aftermarket gaskets like these are total crapola for our cars.....

I used a factory OEM gasket. The car was running fine for about 3 weeks before the oil ended up in the coolant again. There's no leaks under the car.

I just figured that the compression test coming back solid would not 100% eliminate the engine, but at least generally rule it out since the numbers were strong, especially in comparison to the first time I ran it that showed a problem with the head gasket.

The compression shows ok, that's a good sign, but wondering if there might be a very small crack somewhere in the block itself allowing oil to seep thru under pressure (such as only when the engine is on).

Get the radiator pressure tested but allow for a much longer retention period and hope that it maintains the same numbers to eliminate that thought (of a cracked block).

Overheating of an engine can cause stress fractures later.

Did you have the head checked? Over heating can crack or warp a head.

If the head was warped, don't you think the compression test wouldn't have come back with steady numbers?

As for the car overheating, what happened was: we came to a stop at a light, and as I was idling, the temp spiked to 233, for some reason the low speed fan hadn't kicked on earlier, the high speed fan did and brought the temps back to operating range. I monitor off the scangauge often. Only time the low speed fan didn't come on (and before you ask, the fan was recently replaced before the head gasket was replaced and the fuses checked.)

After the HG was replaced, the car was tested at WOT, in traffic, normal driving and there were no issues for roughly 3 weeks - with checking the oil and coolant levels before and after every drive.