Why were so many Subarus from the 90s to the 2000s prone to blown head gaskets? Has Subaru fixed the issue yet?
Poor head gasket design on the normally-aspirated engines made worse because the boxer engine has head gaskets in contact with the coolant at all times, even when not running. (Turbocharged models had stronger gaskets and did not suffer from the problem, but of course turbocharging brings its own issues to the table.) Better aftermarket gaskets are available but gasket replacement involves removing the engine from the car and of course there are two cylinder heads to deal with, so it's an involved job.
The problem began with Subaru's belt-driven overhead-cam engines introduced in the early 1990s, and was fixed about 10 years ago with the introduction of the redesigned "FB" series 4-cylinder boxer engine.
Subaru head gaskets for those generations were a single layer design. it’s rare that they go more than 120k miles without leaking oil from the bottom of the head gasket. Sometimes when the head gasket fails, it will leak coolant into the cylinder or out of the engine.
I had a 2002 Subaru Outback 4 cylinder boxer engine, and we had to change the head gaskets. We were lucky that we caught ours early enough to only have the oil leak from the bottom of the gasket. Bought the new design double layer head gaskets that was supposed to be the fix. My brother-in-law has a 1999 Outback 4 cylinder and he also had to get the head gasket job to fix the leaks.
The newer ones (basically 2012 2013+) don't have anywhere near the amount of issues as the old ones but some models still have defective engines that cause oil burning.
The oil burning as I recall was due to a supplier problem (defective piston rings). Just checked, affected models are 2.5 liter 2011-2014 and 2.0 liter 2012-2013 Subaru 4-cylinder engines.
Good news though if you repair it with the gaskets available today it should stay fixed. Not only were original gaskets “poorly designed” but it was also more of a problem due to cheap materials and manufacturing of the original gaskets used. Problem is some after market gaskets are the same way. When it comes to getting these I would obtain from the dealer and get the redesigned better made ones, or go with a high performance set. IAG makes a performance set but they’re almost 300 bucks. If you plan on keeping the car I’d spend the little extra there.
