Scigheras

So my '00 AP1 is one of those that likes to drink, at least 1L/1000KM. I'm getting tired of having to top off at every gas fill up and the occasional clouds of smoke in VTEC are somewhat ashaming.
I have already confirmed the oil is not going out through the PCV, valve seals are unlikely too as I already rebuilt the head (about 15.000KM ago), and oil consumption was unchanged.

I'm thinking of pulling the head and oil pan, and replacing the piston rings with the engine in the car. I won't be able to hone the cylinders.
Do you think bad piston rings are a common cause of AP1 oil consumption, and could replacing them likely fix it?
Or is it useless to try and more likely to cause new issues, as the cylinder bores could be ovalized anyways, I cannot hone the cylinders, etc..?

I read it's best to go with the newest OEM AP2 piston rings, part number 13011-PCX-024?
And of course I will properly gap and clock the new rings.

Any comments from past experiences or speculative input are appreciated

jyeung528

i haven't seen anyone try this. in theory it should help, wouldn't imagine it would hurt.

i'm interested in your results. good luck.

twohoos

Mileage?
Before starting, might consider getting compression/leakdown #s. The absolute values might not mean much right away (unless there's an obviously bad cylinder), but you can do it again afterwards and see if there's any change.

noodels

With oval bores there is no masking the issue, a hone would also follow the contours of the oval.
Try different oils I guess.

Scigheras

90.000km.
That's a good idea. I think useless for measuring how well the oil control rings seal though? They usually don't affect the numbers from these tests I think. But if I decide to replace the rings, it's a good tool to monitor if the compression rings are sealing.

Exactly, so I'm wondering if it's usually oval bores or bad piston rings that cause the oil consumption.
I have tried multiple oils, a 40 weight seems to use less than a 30 weight. But I think going for a 50 will be too risky for this engine.
Right now I'm just on plain old Castrol GTX 10W-40, as it's cheap.

noodels

They<Honda>used a block plate clamp in the hone process on 04MY> onwards to solve the problems with oil consumption.
IT worked & my 05 engine uses 0 oil nor did my 04 engine.

Slowcrash_101

Rings help for sure but won't eliminate the oil burning. And it won't improve until you break in the new rings. If you're consuming a quart/1k miles rings will cut that consumption to around 2-3k miles/quart. At least from what I've seen. Use the latest rings, most important is the oil control and second rings. The top ring is responsible for roughly 80% of the compression from the piston side, so I'd still change it. Ring gap and orientation is critical.

Scigheras

An oil consumption reduction of 2-3x... not perfect but still attractive. Was this on your own car, and did the improvement last? Happen to have any tips on break-in procedure and length?

Thinking about maybe trying krank vents first too...

Billman250

s2000Junky

Agree with Billman. As imperfect as the current piston/ring seal may be, they are mated. I just dont see how putting new rings on (no doubt ovalized) cylinders will improve sealing. I have no personal experience performing this operation on this engine, but logically thinking through this, its a lot of time/effort with high risks of no/to detrimental outcome. I would rather just run it as is until consumption got so bad that it was effecting good running operation/consuming more then current. Honda max spec as ridiculous as it sounds, is 1Q per 1000 miles consumption on the F20. I had a built engine that got down to 1Q every 300 miles and that was my threshold for replacement. 1Q/1000 is pretty rough though I agree. My current F20 with 80k miles on the clock seems to be around 1Q 1500-1800 sadly. Oil consumption does seem to go up as the oil gets a few thousand miles on it. I would just run the 10/40 standard oil as you are doing for cheap/least consumption.