Bought a 2004 Honda Odyssey with 135k miles in January and learned that it had a bad head gasket. Replaced both head gaskets, and machine shop said the heads/valves tested poor for sealing and recommended a valve job, and milling the heads flat. Despite compression being about 200 PSI on all cylinders (+/- less than 5%) even with the bad head gasket (the bad head gasket would slowly eat coolant, causing an overheat condition if you didn't keep it topped up), I gave them the go-ahead, and provided all new valve stem seals. They said the guides were good.
Since I already had the heads off, I pulled the block and resealed everything top to bottom. Where there was a manufacturer seal available, it got a new seal, and I resealed everything that had Hondabond (RTV). I also changed all possible maintenance items, belts, hoses, etc, $700 worth of new parts, so essentially the only thing I left alone was the mechanicals in the bottom end (pistons, rings, bearings, etc.)
The van runs good, and nothing leaks (haven't observed anything visible on the engine, or drops underneath the car), but what is concerning is that the engine is consuming much more oil than before. We've taken it on two long road trips since all this work: the first was a cross-country trip from Colorado to New Hampshire (5,000 miles round trip). I used Valvoline Racing Synthetic 10w-30, only because I had six quarts of it lying around and nothing to use it in, and I figured the high ZDDP would be a good break-in type oil for the top end. That trip I used about 1.5 quarts of oil, and I changed it when I got back.
I have always used 5w-20 as recommended in the owners manual (except for the OCI mentioned above) for fuel economy reasons, so I switched back to 5w-20 for the second OCI and this time used Castrol Magnatec semi-synthetic 5w-20. That trip we went from Colorado Springs to eastern Idaho and Yellowstone National Park. It was about 2k round trip (we've put 3k on since the last oil change). I had to add a quart of oil mid-way through the trip, and it's already low on the dipstick ready for another quart any day now. So that'll be 2 quarts in 3k, which is somewhat alarming; the engine is in good shape mechanically (as far as I know), and with new seals on the upper end and no leaks, that only leaves rings as a possible culprit (to my knowledge) unless the machine shop screwed up somehow in installing the valve seals.
Am I worrying too much over this? This is not the VCM-equipped Honda motor that is known for consuming oil-- those began in 2005. I know new engines have a break-in period where excessive consumption can be considered normal, but I always thought that was due to rings seating, and had nothing to do with the upper end. Is it possible there's something still "breaking in" with the upper end work, where oil consumption will return to normal, or is that wishful thinking? Would it be wise to try a higher viscosity oil for the next OCI? Perhaps Mobil1 0w-30 or something similar?
To put it into perspective, I have three other vehicles and none consume anywhere near the amount of oil as this one now does. My '96 Nissan Maxima has 212k miles, and it's also 3k into it's last oil change, and the level on the dipstick hasn't moved an inch, and I'm even using full-synthetic Castrol Syntec in that one.
What gives? Is there anything I can do to try and narrow down the cause? Or should I simply continue driving it and see if it gets better? Is there anything I could have done while installing the cylinder head that could cause oil consumption? Any info, suggestions, tips, etc. would be greatly appreciated!
Since I already had the heads off, I pulled the block and resealed everything top to bottom. Where there was a manufacturer seal available, it got a new seal, and I resealed everything that had Hondabond (RTV). I also changed all possible maintenance items, belts, hoses, etc, $700 worth of new parts, so essentially the only thing I left alone was the mechanicals in the bottom end (pistons, rings, bearings, etc.)
The van runs good, and nothing leaks (haven't observed anything visible on the engine, or drops underneath the car), but what is concerning is that the engine is consuming much more oil than before. We've taken it on two long road trips since all this work: the first was a cross-country trip from Colorado to New Hampshire (5,000 miles round trip). I used Valvoline Racing Synthetic 10w-30, only because I had six quarts of it lying around and nothing to use it in, and I figured the high ZDDP would be a good break-in type oil for the top end. That trip I used about 1.5 quarts of oil, and I changed it when I got back.
I have always used 5w-20 as recommended in the owners manual (except for the OCI mentioned above) for fuel economy reasons, so I switched back to 5w-20 for the second OCI and this time used Castrol Magnatec semi-synthetic 5w-20. That trip we went from Colorado Springs to eastern Idaho and Yellowstone National Park. It was about 2k round trip (we've put 3k on since the last oil change). I had to add a quart of oil mid-way through the trip, and it's already low on the dipstick ready for another quart any day now. So that'll be 2 quarts in 3k, which is somewhat alarming; the engine is in good shape mechanically (as far as I know), and with new seals on the upper end and no leaks, that only leaves rings as a possible culprit (to my knowledge) unless the machine shop screwed up somehow in installing the valve seals.
Am I worrying too much over this? This is not the VCM-equipped Honda motor that is known for consuming oil-- those began in 2005. I know new engines have a break-in period where excessive consumption can be considered normal, but I always thought that was due to rings seating, and had nothing to do with the upper end. Is it possible there's something still "breaking in" with the upper end work, where oil consumption will return to normal, or is that wishful thinking? Would it be wise to try a higher viscosity oil for the next OCI? Perhaps Mobil1 0w-30 or something similar?
To put it into perspective, I have three other vehicles and none consume anywhere near the amount of oil as this one now does. My '96 Nissan Maxima has 212k miles, and it's also 3k into it's last oil change, and the level on the dipstick hasn't moved an inch, and I'm even using full-synthetic Castrol Syntec in that one.
What gives? Is there anything I can do to try and narrow down the cause? Or should I simply continue driving it and see if it gets better? Is there anything I could have done while installing the cylinder head that could cause oil consumption? Any info, suggestions, tips, etc. would be greatly appreciated!
