This article says that in
This article says that in "1999 subaru switched to a multilayer steel shim gasket." And then again switched to the same steel gasket in 2009, to fix the problem. Very confusing, and must be a typo. So they have been using the same steel gasket since 1999 and it has failed? All steel gaskets are layers of stainless steel with a Viton rubber coating on them, and they are awful gaskets, that must be used on an engine that is polished to a level 80 RA finish or greater, it has to be almost mirror smooth. I know because I saw a steel shim gasket fail on a Tercel due to a single machine tool mark on the block, it was less than 0.001" deep, it was a single scratch from the factory Toyota milling tool that milled the block, and the steel shim gasket still failed and leaked coolant into the engine after about 10,000 miles of putting on the head gasket. The steel shim gaskets don't work as well as the graphite gaskets, the thick graphite gaskets actually are more forgiving and more squishy and when you remove them, they are absolutely glued on to the block, and they allow the aluminum cylinder head to slide all around on top of the block, without any leaking. You need a lot of flexibility which is why they used graphite gaskets in the first place. The problem is NOT from coolant. The problem is because Subaru is the worst engine ever, and they use an "OPEN DECK" block design, which has too much flex, the entire block flexes and expands a lot, and then contracts a lot, and the open deck doesn't provide any rigidity. High performance engines don't use an open deck, and they have to close the deck by welding the deck solid on racing engines. There are some Subaru engines with a "closed deck" but they cost twice as much for Subaru to make, and those NEVER blow head gaskets (I can't confirm this actually, but I've heard they don't have any problems, it's really the cheaper newer open deck engines that have started blowing gasket). My friend had a 1995 Subaru Turbo with almost 300,000 miles on it, and he ran it like a race car, and I believe it had a closed deck 2.2L engine, and it never had a single head gasket issue, and he basically tried to destroy that car, running it into the rev limiter every single day.