Nave43

I drive a 93 Del Sol Si - 209k on the body
D16A Engine swap w/ about 166k on the motor
OBD1
No substantial engine mods besides a Ram intake

Before i had 5w-30 Castrol GTX semi synthetic w/ a Mobil 1 filter. Put in 5/5/14
Oil was changed w/ 5w-30 Royal Purple full synthetic about 1000miles ago
Also replaced filter with a new Mobil 1 filter at the same time 9/5/14 to be exact

So onto my problem, i have never had a problem with oil loss on this engine since i got the car. I check the oil regularly because i am **** like that. Though today i went to check the oil and it was about an 1/8-1/4 quart low. I topped it off to the correct level w/ more Royal Purple Full synthetic.Then quickly checked under the block, my spark plug wells, oil filter, and coolant and found no signs of oil or leakage. The vehicle never makes blue smoke although it does run rich at times.

To my knowledge oil can only go three places, Coolant, Leak, Or burn off. Though there are no signs of any of those problems. I know full synthetic is more prone to leaks but that doesn't seem to be the case. I dont have the tools to do a compression test or that would be my next step. Sorry for the long post but really looking for adviceas to what the problem could be and wanted to make sure i had all the details down off the bat.

Thank you in advance

JPRhome

Have you checked if the valve cover is leaking around the timing cover area where its hard to see? my D15B7 had that issue.

Also do a test under the hood while engine is running in park neutral whichever then give it a nice 1/4, 1/2 throttle for a second or two and see if blue smoke pops out the tail.

if the oil was coming out anywhere else I think the engine would have issues running unless its leaking out your rear crank seal.

TomCat39

It seems pretty commonly said that older Honda engines tend to burn full synthetic faster than conventional oil.

I suspect the looser tolerance of the oil control rings is not as successful at scraping the tighter molecule synthetic off the walls as cleanly as it does with normal conventional motor oil.

Try going back to your semi synthetic or even conventional motor oil and see if it still consumes your 1/8th to 1/4 liter.

And just as an FYI, Honda proclaims up to 1 liter per every 1500 Kilometers is normal consumption. It's not until the consumption passes that, that they will rip into a motor.

Oh and Napa Gold filters are Wix oil filters. Some of the best built standard oil filters on the market. I am not sure oh Mobile 1 filters, I am skeptical they are made by Wix so don't think they are as high of quality.

Nave43

The thing is it runs so much better with the royal purple in it, its quieter, smoother, and i even get better mpg. Secondly i check it regularly, i checked it not even 300 miles ago and it had not moved... It seemed to of happened all at once. That is what i found so strange, i never even drove it hard in that time period. I haven't even hit Vtec in that time period except for once or twice (usually only around 2-4rpm). Wouldn't i have noticed it earlier on? Its been 1000 miles and i have checked it at least 5 times. Its been colder outside could that effect it?

TomCat39

I don't believe so.

All I can suggest is monitor it (like I need to tell you. ) and see.

There are a couple of places it can leak oil that you wouldn't see for quite awhile. One is in the distributor, another would be the cam seal, it's behind a cover and the oil would run down under the covers before building up enough to look like a front main seal. Another place is the spark plug tube seals. Not sure if the D16A has the dual set or just single seal set like the D16Z6.

I wouldn't think any of those would leak enough for that much oil loss without being noticeable but who am I to say either way.

Nave43

I wont be able to look at it closer until day after tomorrow, but at that point i am going to get all up in there and see if i find any wet spots. I keep my block clean so it should be easy to tell if i find one.


Check list
Distributor
Valve cover
Under Timing belt cover
All around were bellhouseing bolts on

PCV Valve ? I have a filter on mine it doesn't run to my intake, so i will check the inside of the filter as-well.

I will also try "JPRhome" idea. I looked for blue smoke but not with someone else stomping the gas.

My spark plug wells are dry on top, but i will take the plugs out and look even closer because now that you mention it im not sure if its single or duel seals either. If it was underneath the plugs i think i would have developed a misfire though.

If all this fails go to advanced auto or something and do a compression test... I should probably do that anyhow....

TomCat39

Dual seals won't leak under the plugs. You either get it from the top of the tube (yours is dry) or the bottom of the tube on top of the plugs. You get wet wire tips with dry top of tube if the bottom tube seals leak.

Common on the D15B7 and D15B8 motors. I think after 95 they changed that design for the one piece metal tube design of the D16Z6 style motor.

Nave43

Ok then in that case, my spark plug wells are perfect.

Nave43

Thread Update:

Since i last posted i had to add another 1/2 Quart or the RP before this oil change to keep it topped off.

Its been another 5k already and a long winter. That being said i haven't been under the hood much. Yesterday it was warm and i changed the oil among other things. When i got under the hood the leaks are now obvious. There is even oil throw onto the hood by the power steering...

I believe its leaking from 3 places.

The side of the valve cover near the timing belt cover.
PCV Valve. (Which is cheap and getting changed ASAP)
And maybe from the cam seal and or Crank seal but it may just be running down from the valve cover.