I bought this car after owning two other Bonnevilles and not having a major problem with them. In the summer I bought the 02 I'm talking about hoping the have the same luck. Since then I've hit every common problem with that car other than the lim/uim failure and window regulators.

I decided to take a look and see when the Intake was manufactured to see if it was replaced. The manufacturing date was the very end of 03 and my car is an 02. So, I know that has been replaced at least once and the DexCool was replaced with the Prestone Dex.

Well, in the winter I noticed that my reservoir tank was low so I filled it back up with the Prestone and gave it a week and it was gone. I filled it up again and gave it a week to check and I didn't lose any. I checked today, two months since I last put it in, and it'* at the same level as it was back when I filled it.

I've checked for about every sign for a failure and didn't have any. My oil was the same honey color it should be, I didn't smell any being burned off, my engine is running like new, and I didn't have any puddled around the intake. The odd thing is that I had a greenish goop around the oil fill tube. I wiped it with a paper towel and it was a neon green similar to the color of regular antifreeze. I smelled it to see if it was coolant and the only smell I could get off it was a gasoline smell. I've never had green antifreeze in this car and I've never put any oil or gas additives in my car.

Anybody have any idea what this is? BTW, I've been running Valvoline Max Life Synthetic oil and Shell V-power gasoline the entire time I've owned this car if that has any affect on it.

The upper may have been replaced but perhaps not the LIM gaskets. If you are sure you have an internal coolant leak, my suggestion would be to tear it down and install aluminum frame LIM gaskets ($60). While it is apart, you can examine the UIM carefully for evidence of softening around the EGR bore. If the plastic is still sound, you could just replace the UIM gasket ($40) and add a heat shield ($10-20) for the UIM. Or, to be done with it forever, change out the UIM using the APN UIM kit for $115. For your newer LIM, you might consider having the base of the APN stovepipe machined from .749" to .624" OD to provide the largest insulating gap between the hot stovepipe and the vulnerable plastic.

Finally, those of us that think any Dex is bad Dex would recommend you flush and fill with the yellow "mixes with any color or type" extended life coolant.

If you've never had green coolant in the car, as you stated, I would venture to say that it is the color that the regular honey-colored oil gets when it gets dirty with outside engine grime, and a bit of gas.

I would clean it off, make sure the dipstick is on tightly and plenty sealed, and see if it returns.

I cleaned it off today and drove about a 100 miles and took the cap back off and it was still clean. This makes makes me glad that I don't have any signs of the failure now but it makes me mad that I don't know what it was on there.

I'm going to drain that Dex out of my car as soon as I can. I can't afford to have that eat away at my gaskets. Just last week I had to have the transmission worked on for the pressure control solenoid. I managed to have them lube my steering shaft for free while they were working on my car. So two problems off the list.