jdmdohcpower

I helped my brother in law get into an 03 with 100k that was a 1 owner 60 year old woman, I met her so I know this is the case. Shortly after he got the car the cat blew. I replaced with a walker that blew, I replaced with used oem that may have been damaged from the start so got another used oem. When installing tonight I noticed way too much black soot for the 200 miles of being on the car. This car is burning about a qt of oil every tank of gas. Im thinking rings, did compression check and a solid 240 on all 4 and all plugs looked good and dry. I put in edge 10w 30 in when he got the car and he has been topping off with Mobil 1. No change in oil burn amount. Pcv was just changed but have not driven yet to check and I doubt a qt every tank of gas is the PCV.

Any thoughts as to what else could cause this kind of oil consumption? I don't want to replace the cat until this is solved as its just going to blow.

rmerchant3

Have you done a leak down test yet?

rrounds

Try some 10/40 H/M oil or 15/40 HDEO like Rotella or Delo 400 Multigrade SAE 15W-40 and see if you use less oil.
On my old R6 that use to suck oil past the rings, I ran 1 qt. of st. 40w with the rest 15/40 and that cut oil consumption by over half.

ROD

s2000Junky

1Q Every tank (250-300M) is beyond excessive, its a damaged engine. The majority of the F20's use oil, anywhere from 1Q per 1000miles to 3000 Miles. If its at the higher consumption rate, I think its safe to say the 60 year old woman (like most I know) aren't good about checking and topping off oil when its needed, they wait until the recommended oil change and where ever the level is at after 3-5k miles is where its at. This obviously is going to create slow long term damage to the engine. Your likely getting oil burn from both the rings and valve guides. It is possible to have good compression rings, but failed oil control rings. But typically at your rate of consumption if indeed accurate, your usually going to find a cylinder or multiple with low compression and signs on the plugs.

Also as a tip, Mobil one has proven to have one of the highest cook off rates over any of the other synthetics, so naturally oil consumption is going to go up when using/topping off with this oil. Your better option is to use a standard oil and 10/40 would be the best, but dont use 20/50, its too thick for the tolerances on this engine and will just create more damage. Standard oil typically consumes at a slower rate, not to mention the lower cost if your using a lot until you get the problem addressed.

jdmdohcpower

My gut said rings but no signs at all. I don't think that the oil rings would be bad and the compression ring would be so good. Doesn't make sense to me.
Any other things to look for or to confirm or deny this

jdmdohcpower

Valve stem seals /guides?

zeroptzero

How do the plugs look ?, check them and see if they indicate any issue. Try one of the oils rrounds (Rod) suggested above, see if it makes any difference.

Does the oil have a heavy fuel smell ?, the engine could be running too rich (which also kills cats) and washing down the cylinders with fuel which will affect oil consumption. Checking condition of plugs for issues.

Oil rings could be gummed up with varnish, if the previous owner may have run the oil too long and/or used lower quality oil.

jdmdohcpower

Plugs look ok. slightly greyish white but not fouled. I was thinking pulling the plugs and pouring some seafoam In there overnight?? Think that's worth a shot of the rings are gunked up?
Don't smell fuel nor do I see how it would be running that rich since its bone stock and I don't see any apparent issues with idle or what not

zeroptzero

Hard to imagine burning one quart of oil per gas tank and not having oil soaked/sooted plugs. The oil must be going somewhere else

Be careful with Seafoam in the cylinders, you can hydrolock the engine if not done right, make sure the spark plugs are out when you crank first crank it over.

For a longer clean interval check out auto-rx.com , it's a well respected cleaning product. Also start running a high quality synthetic after the cleaning process is done.

afzan

I don't think I'd want an AP1 that was owned by a 60 year old woman.

Strictly because I'm not confident she would've been checking the oil and topping it up every 500-1000 miles