An old van was recently towed in with the complaint that it had died on the road. Some checking revealed a situation that prompted our office lady to label it the "Pepto-Bismol car." Both the radiator and the transmission were full of a pink, foamy liquid that looked like the famous medicine. But in this case, instead of easing gastric distress, this liquid was going to cause considerable pain in the butt, or wherever the owner carried her wallet.
What happened is the transmission oil had mixed with the antifreeze, putting oil in the water and water in the oil. The culprit was the transmission cooler, which is a tube that carries transmission oil through the radiator tank to cool the fluid. The tube had sprung a leak into the radiator, allowing the two fluids to mix. This would require a repair or replacement of the radiator to fix the leaking cooler, but there was a snag. The car had stopped going, while she was driving. The transmission began slipping so badly that forward motion stopped. This would mean that the transmission had taken in so much water, which doesn't lubricate as well as oil does, that the clutches had to have burned out. Now it would need the transmission rebuilt or replaced along with the radiator.
Mucho bucks. More than the van was worth. We hate to give up; after all, fixing cars is what we do. But, in this case, we suggested that she scrap the car and start over with another one. She agreed, and we helped her call various scrap yards, and soon had several of them bidding against one another to buy her van. She ended up getting $450 dollars for it. I'm sure it was hard to swallow, but necessary, like taking Pepto-Bismol.
Could it have been avoided? Possibly. if someone had been checking her fluids often enough, and had known what the symptom looked like when the leak started. If it could have been caught before the transmission burned out, it would have been much cheaper to repair. The symptom for oil in the water is that it looks oily, feels oily, and if you put some on your hand it doesn't rinse off with water. Antifreeze feels oily, but is water soluble, so it will rinse off easily, oil will not. The symptom of water in the oil is foam. In the engine, which has dark brown oil, it will look like milk chocolate on your dipstick. Transmission oil is reddish, so it will look like Pepto-Bismol when it foams.
Neither situation should be ignored. Immediate repairs are called for, because oil ruins rubber, like radiator hoses, and water doesn't lubricate well enough for engines or transmissions to survive.
The usual suspects for these problems are the engine oil cooler and the transmission oil cooler. Both are usually located inside the radiator tanks, where they can't be seen, so inspection of the fluids is the only preventive option.
There is an old adage about pouring oil on troubled waters, but don't do it. If it's in your car, it will cost you, and if on the ocean the Coast Guard will arrest you.