Over the years there has been a lot of talk about Lower Intake manifold gasket failures. Dex-cool has taken the brunt of this myth. I decided about a year ago to do a year long experiment that would help shed some light on this issue. During this time I also did a lot of research. And now that I have finished this little experiment, I want to share my findings. My observations involve a few cars, but mostly my own.

First up, a LIM gasket failure. This is a plastic framed gasket, standard on our engines. Running Dex-cool, again, standard on our engines. For about 95,000 miles. Please note there is green coolant in this engine. I had flushed the system shortly before changing the gaskets.


Here is a close up. This is a classic failure. The belief is, Dex-cool was acidic and caused the gaskets to soften and fail.


The common fix for this was to drain, flush and refill your coolant system with a common green coolant. The problem with this is if you don't get all the Dex-cool out, it will react with the new green coolant and sludge up.

This here is the same style of plastic framed gasket. The difference here is this is about 12,000 miles using Peak green coolant. As you can see, there is a classic failure starting.


It is obvious that changing coolant did not correct this problem.

Now, these gaskets are the new aluminum framed gaskets. These were from a engine running Dex-cool. As you can clearly see here, there is no sign of classic failure.


It should be clearly obvious that changing the gaskets to the new aluminum style fixed this problem.

This article has been presented to you to help you make a good, educated decision on what is best for you engine. It is my advice that changing the LIM gaskets to the aluminum style is the best choice. There is no reason to change your coolant type. Don't fall in to the hysteria that you must change your coolant. What you do with this information is totally up to you.

I will keep adding more images as they come in.

Plastic framed gaskets with Dex-cool, unknown miles. This gasket has a slightly different design then earlier gaskets.