M104 valve guides
If your head gasket started to leak at 130,000 miles, I can be almost certain that it was replaced before. I have NEVER EVER seen a head gasket on an M104 go that far without leaking.
You can expect to pay in the neighborhood of $2000.00 for a head gasket job on an M104 with valve guides and seals. If your engine cable harness has not been replaced already, it will probably get disturbed when it is moved to do the job. Count on another $800.00 or so for that.
I doubt that you will notice oil loss on the dipstick due to leakage of the head gasket--it would have to really leak ALOT of oil to make any noticeable difference on the dipstick. Basically, you can put the job off until it makes enough of a mess that you are bothered by oil on the ground under your car, but you are only postponing the inevitable.
I get varying answers, but the head gaskets supposedly have been improved. I still have seen many leak a second time, albeit after 60,000-90,000 miles, instead of after only 30,000-60,000 miles.
Head gaskets made by Goetze supposedly last longer. I have been unable to find a dealer or parts supplier that sells that brand. All dealers in my area sell Ehlring head gaskets for this motor.
Anyone know where to get a Goetze head gasket for an M104?