Compression Issues

[Retro-Cow]

Hey all,
I just got around to doing a compression test. The results weren't good.
Every cylinder is around 100psi except for cylinders 4 and 6 which were about 90 (head gasket?)
A wet test showed about a 10psi increase on each cylinder.

This is indicative of worn piston rings right?

I should also note that when I did the compression test I didn't have the equipment to check the battery, but I assume that it wouldn't cause this much of a fluctuation even if the battery was low...
Also, I don't know when (or if) the previous owner did the timing belt but that wouldn't be the cause of consistent low compression across every cylinder right?

[icemaninlv]

Put a little bit of oil in each cylinder and let it soak a few minutes. then preform the test again. if the values go your looking at rings.

but with that low you can pretty much be sure rings.

[itsa300zx]

A strong charged battery is also important.

[Retro-Cow]

Yeah but would a weak battery cause 20psi+ of variance?

[icemaninlv]

I just did mine and in order cyl 1 through 6 was
170
155
140
160
160
160

In cylinder 2 I added a cap full of oil and it jumped to 190psi

A weak battery will just take forever to crank, compression doesn't care about the speed of the stroke just the distance traveled of the piston compared to when the valves are released

[Retro-Cow]

Okay that's good to know.
Also as mentioned in my first post when I added a little oil it only jumped about 10psi in each cylinder. I definitely didn't see as much of a jump as you did.

[itsa300zx]

I believe rpm of the engine does matter for a comp test. As per the Nissan FSM, "be sure the battery is full charged to obtain specific engine speed".All comp numbers are referenced at 300 rpm, which is the the starter does at full charge.