The concern is the amount of oil consumption. Cat or not has no influence on this.

^ I couldn't tell how much oil consumption he was referring to, other than saying it consumes enough oil for normal driving ? It might help to know what oil consumption level the motor is experiencing though, in quarts / 1000 miles.

The Original poster said 1Q in 3k miles. But my response was in regard to the most current poster a few back "Nippon" who stated 1.5Q in 3k miles and did a full valve guide/seal replacement with still no change in consumption reduction.

Finally got the car out this past weekend.

Had gone back to 10w30 oil in it.....

Still getting smoke, and its back to blue.

Only other thing left to try is the OEM cat instead of the Berk HiFlow cat.

You have to change the valve guides.It's the last you should do to make sure the head is ok.The misfires you saw back then is a common symptom of worn valve guides/valves.You'll be lucky if the problem is the head.Otherwise you are messing with the cylinders/pistons/rings which is difficult to repair and very expensive.Hope that's the cylinderhead.

The OP said he changed them. I still think they are suspect as the symptoms fit worn valve guides.

To the OP, are you sure the guides were replaced and not just the seals? Are you sure the machinist actually did the work? I had a machinist try to convince me once to knurl the guides instead of replacing them because it was easier for him. Hope you don't mind me challenging you on this, but as I said above, the symptoms fit so well, especially for a higher mileage head, I wanted to be double check that you don't think they were changed when they were not.

I'll have to see if I can find the paperwork for when the valve guide seals were replaced, but I'm pretty sure it was just the seals, and not the guides.

my information was in regard to grey/whitish smoke, if you have blue smoke it is oil getting into the combustion chamber somehow. If it smells like burning oil then it likely is.

Thanks for the info :thumbup: Consumption rates aren't too bad, perhaps more than what the owners expected though given their attempted repairs.

I recently bought my first old school Honda that does not burn oil, it is a 2000 Acura GS-R with 190,000 kms on it, it does not burn a drop much to my surprise and I've been putting it through its paces. My 10 previous Hondas all burned some oil. My newest Hondas - 2016 Civic turbo and 2017 Hr-v don't burn any oil yet, so far so good.

I bought a used head(perfect condition),took it at a specialized machine shop with new ferrea valve guides and oem honda valve seals.After 3 days i took the cylinderhead from the machine shop(the new guides were easy to see) and went to my mechanic.He swapped the "new" head with the original one.I was there all the time,just in case...Unfortunatly,nothing changed:(.I was sure that the guides were the problem but i was wrong.The thing that drives me crazy is that if i got worn piston rings or worn cylinder walls,how the hell the compression test was fine(3 times checked/225-230 all 4)????