I have a Shimano 105 BR-R7070 hydraulic disc brake and just discovered that the front caliper is leaking oil from one side of the pistons. I'm wondering if this is fixable? If not, what replacement shall I get? I can't seem to find 105 disc brake calipers anywhere. Is it compatible with other calipers and what would you recommend?
Usually, with leaking Shimano brakes, the piston has cracked. Have you changed the brake pads or otherwise messed with the pistons lately?
Aftermarket pistons and seals are available, but that would be a non-authorized hack job that Shimano does not authorize. Don't expect to keep your warranty if you do so, and your safety is no longer guaranteed. Up to you if you think it's worth it.
Every Shimano caliper is interchangeable in terms of functionality.