Oil Burning Mystery

Joined
Jan 5, 2008
Messages
485
Location
New Mexico
I own a 1993 Accord with about 300K on the Stock Bottom end. Ever since I acquired it back in 2015 with about 160K it has used about 1 to 1.5 Quarts of Oil in 3000 miles. I change the Oil every 3000 miles. Last year I pulled the Head and replaced it with a Junk Yard head from a doner that had about 150K miles on it. I removed and cleaned the valves, replaced the Valve Seals and seated the valves with valve grinding compound. (Took the Head to a machine shop to check for leaking) I used all OEM supplier (Victor Stone) gaskets and replaced the Head Bolts.

After the Head job the Engine still had the same oil consumption issue. However I couple weeks ago I took the car on it's first long Trip. Albuquerque to Fort Worth Texas (648 miles). I was in the middle of an oil change interval so I only topped off the oil before the trip. When I arrived in Fort Worth I waited until the next morning and checked the oil. I was a Full Quart Low!

I added a Quart before the Trip Back to Albuquerque, after I arrived, I waited until Morning and was shocked that the oil Level was still at the top of the dipstick. I changed the oil for a trip to Oklahoma City. I just arrived from the round Trip journey and the oil level did not change. Can a car stop consuming Oil? Any Theories?
 
Italian tune up on the highway free'd up the rings a little bit?
Possible because my oil consumption actually went up after the Head Change. I think the carbon removal and fresh Head put more pressure on the Bottom end. My Compression was 155 PSI +/- 5 PSI on all cylinders (Low but still in spec) after the Head Work. I should check it again.
 
This was normal weirdness when I owned a Subaru. Some highway drives consumed a bunch of oil. Others didn’t. It was consistently and meticulously maintained. Never found the pattern.

you might start running a half can or so (your call, not everyone likes this) of seafoam in every oil change for the next couple of years. I’ve had some wild results with that and high mile Volvos.
 
I had a ‘90 Civic that had been ran hot/overheated multiple times by its previous owner, hot enough to bow the head, took out a couple exhaust valves. Had a buddy resurface, do a valve job, and replace the bad valves & seals. Put it together, burned oil like a freight train! Took it apart again & replaced the coked up rings, honed cylinders, new .001 undersize rod bearings-put it back together, drove it for years! I bet yours could be done without pulling the engine too.
 
I had a ‘90 Civic that had been ran hot/overheated multiple times by its previous owner, hot enough to bow the head, took out a couple exhaust valves. Had a buddy resurface, do a valve job, and replace the bad valves & seals. Put it together, burned oil like a freight train! Took it apart again & replaced the coked up rings, honed cylinders, new .001 undersize rod bearings-put it back together, drove it for years! I bet yours could be done without pulling the engine too.
So he just replaced the Rings not the Pistons and just did a Re-Hone with the block in the car. If the oil burning comes back this sounds like a plan. Easier than looking for a used low mileage Short Block.
 
The oil control rings (1 on each piston) could be clogged. Do you have any maintenance records from the previous owner/s? Search this forum for solutions for cleaning clogged oil control rings.
 
1qt/3k is not bad for a 300k engine. Highway miles can be easier on the engine & with a long trip the car's engine may of warmed up enough to free up the rings a bit to seal better. Along with easier miles consumed less oil. You're getting your money's worth out of this car. Just keep checking the level as you're doing & add as needed. If it consumes more again when driving locally maybe try a thicker high mileage oil?
 
Possible because my oil consumption actually went up after the Head Change. I think the carbon removal and fresh Head put more pressure on the Bottom end. My Compression was 155 PSI +/- 5 PSI on all cylinders (Low but still in spec) after the Head Work. I should check it again.
Low compression means more oil getting past the rings. So chances are either your rings are stuck or the cylinders are worn and are scored, causing low compression and oil consumption.
 
Update, I had a thought this morning. I forgot to mention that when I got off the Highway when I was almost in Fort Worth my Throttle was sticking. My car was revving about 2500 rpm. I needed to tap the gas pedal to get the idle to go back down to normal. The next day I used this can of Cleaner to spray my Throttle Body. I had recently replaced my stock intake manifold with a 94 Prelude Intake Manifold so this trip was sort of a Test. After cleaning my Throttle Body with the car running, my car has stopped using oil. I really needed to keep the revs up to keep the car from stalling. I used about half of this can when I was cleaning out the shaft and Butterfly. Its possible that the cleaner may have cleaned the Rings? This solvent contains hexanes, difluoroethane and n-pentane.


IMG_20240120_093135105_HDR.jpg
 
1qt/3k is not bad for a 300k engine. Highway miles can be easier on the engine & with a long trip the car's engine may of warmed up enough to free up the rings a bit to seal better. Along with easier miles consumed less oil. You're getting your money's worth out of this car. Just keep checking the level as you're doing & add as needed. If it consumes more again when driving locally maybe try a thicker high mileage oil?

I second this. It maybe too late to go synthetic but OP should consider getting oil from Costco, which sells various brands at much better prices than local stores. I love their Warren-made Kirkland full synthetic 0W20 that cost less than half of Mobil 1.

If this is my car, I would add 1/4 quart every 1k mile or possible go to 10W30 or heavier weight oil if driving condition never drop below 32 degree F. 3k OCI is really too short for Honda so maybe doijg 5k OCI and out 1/4 quart in per 1k. As long as the oil level is between the high and low mark, there is enough oil, especially if you drive frequently so the engine is very really dry.
 
My car burns a quart every 3k and it has just under 200k miles on it. I figure it's pretty normal. i hope it magically quits using oil but I doubt it will.
 
Highway runs generally provide high manifold vacuum for longer periods, sucking more oil vapor through the PCV valve. By what I've seen, this is the main reason why highway runs tend to consume more oil in engines that do burn oil. Yes engines can slow or stop their oil consumption if they were initially neglected and somehow still in decent condition, then start receiving better maintenance and "Italian tune ups." But not always.
 
My car with 220K consumes about 1Qt per 2K miles, unless I am spending a lot of time near the redline, in which case it will use a quart in ~ 800 miles. I bought this car new and the oil consumption was the same when purchased. I was offered a replacement engine under warranty, but everyone I knew with the 6mt/revup combo had about the same consumption and I didn't really want them tearing my new car apart.

In short, I wouldn't be concerned with 1qt/3K miles at 300K. I would not be inclined to tear it apart to possibly make it better. If I was going to do that, I would do a full rebuild and essentially start over with zero miles. Then you have to do the same to the transmission, then the A/C quits working. I would just drive it.
 
Highway runs generally provide high manifold vacuum for longer periods, sucking more oil vapor through the PCV valve. By what I've seen, this is the main reason why highway runs tend to consume more oil in engines that do burn oil. Yes engines can slow or stop their oil consumption if they were initially neglected and somehow still in decent condition, then start receiving better maintenance and "Italian tune ups." But not always.
I neglected to mention that high manifold vacuum translates to higher cylinder vacuum, which tends to pull more oil past the rings into the cylinders, in engines that already burn oil.
 
I have a 2015 Honda Accord 2.4L and have used 0W-20 synthetic oil, WIX filters BG CVT transmission conditioner with new fluid every 30K and with Chevron Techron, Royal Purple, Lucas and many more fuel/injector cleaner s
ince new. The car just turned 150K with no problems. I have an unlimited power train warranty so I'm faithful to maintain for all of my cars. Napa Full Synthetic (Valvoline)

2015 Honda Accord 2.4L
2017 Mazda CX-5 2.5L . 125K
2019 Toyota Prius 100K
2006 Honda Civic DX 1.8L
 
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