This is why you want a 30 weight oil.
06-12-2011, 07:13 AM
#1
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This is why you want a 30 weight oil.
2 recent posts made me follow the oil supply to the head.
One was the "VTEC doesn't work" post and the other was the "Oil flow through engine" post.
Here is what I found:
This is the oil supply to the head - there is only 1, this one.
All the oil ends up here: into the VTEC Solenoid Housing.
The VTEC valve is removed here.
The oil enters at the bottom, goes through the small hole in the top right corner and out the tiny hole in the chamber above.
As you can see its pretty small, about 2mm in diameter. (0,078")
This passage is always open, no matter what, always.
Below VTEC rpm this is the only oil passage to feed the valve train.
So right after a cold start, all the oil the head will get has to go through that 2mm hole.
Makes you think.. huh?
Passed through the VTEC solenoid housing it enters this hole.
Both holes are pretty big to allow enough oil through during VTEC, to keep the rokers locked.
The hole above leeds to the small arrow at the left.
Oil flows around the head bolt to the exit, the bigger arrow, into the bottom of the #1 lower cam tower.
There is a hole all the way through to the next head bolt, but its a dead end.
That hole is needed to connect the head bolt hole to the lower cam tower exit.
Again: large diameter hole needed for VTEC.
Bottom view of #1 lower cam tower.
Oil enters at the left and exits into both rocker shafts, they are hollow.
Always, the rockers need oil all the time.
The small hole in the middle feeds the chain gear.
This tiny hole is the one-and-only feed for the cam journals, one hole per camshaft.
No matter how big the holes are in the beginning, this is it, about 1.5mm diameter (0,06")
Its pretty small.
It has to feed 5 cam journals, even at 9000 rpm.
All the oil for the cam journals has to go through this, the cam is hollow, to get to the rest of the journals.
It is not hard to imagine, cam journal #5, closest to the firewall, will not get all the oil it needs right after a cold start using thick oil in the winter with such a small feed as seen in the picture above.
Not even using thick oil in the summer.
So...
Nothing but 0W-30 for me.
One was the "VTEC doesn't work" post and the other was the "Oil flow through engine" post.
Here is what I found:
This is the oil supply to the head - there is only 1, this one.
All the oil ends up here: into the VTEC Solenoid Housing.
The VTEC valve is removed here.
The oil enters at the bottom, goes through the small hole in the top right corner and out the tiny hole in the chamber above.
As you can see its pretty small, about 2mm in diameter. (0,078")
This passage is always open, no matter what, always.
Below VTEC rpm this is the only oil passage to feed the valve train.
So right after a cold start, all the oil the head will get has to go through that 2mm hole.
Makes you think.. huh?
Passed through the VTEC solenoid housing it enters this hole.
Both holes are pretty big to allow enough oil through during VTEC, to keep the rokers locked.
The hole above leeds to the small arrow at the left.
Oil flows around the head bolt to the exit, the bigger arrow, into the bottom of the #1 lower cam tower.
There is a hole all the way through to the next head bolt, but its a dead end.
That hole is needed to connect the head bolt hole to the lower cam tower exit.
Again: large diameter hole needed for VTEC.
Bottom view of #1 lower cam tower.
Oil enters at the left and exits into both rocker shafts, they are hollow.
Always, the rockers need oil all the time.
The small hole in the middle feeds the chain gear.
This tiny hole is the one-and-only feed for the cam journals, one hole per camshaft.
No matter how big the holes are in the beginning, this is it, about 1.5mm diameter (0,06")
Its pretty small.
It has to feed 5 cam journals, even at 9000 rpm.
All the oil for the cam journals has to go through this, the cam is hollow, to get to the rest of the journals.
It is not hard to imagine, cam journal #5, closest to the firewall, will not get all the oil it needs right after a cold start using thick oil in the winter with such a small feed as seen in the picture above.
Not even using thick oil in the summer.
So...
Nothing but 0W-30 for me.
06-12-2011, 08:54 AM
#2
Registered User
I agree.I run the Amsoil AZO 0W-30 oil in all my cars listed below.03S has 78k miles,02Z has 64k miles and 96 GST has 143k miles.Most wear can occur at startup.
Sometimes my cars may sit for 2-3 weeks without starting,so I want all the start-up protection I can get.
As always,IMO.Results & Opinions vary.
\rlr
carolina
Sometimes my cars may sit for 2-3 weeks without starting,so I want all the start-up protection I can get.
As always,IMO.Results & Opinions vary.
\rlr
carolina
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06-12-2011, 08:47 PM
#8
I'll hazard a guess that many conventional 5w30 weight oils in the late 90's were just mostly thin oils with lots of viscosity index improvers to make them act like thicker oils when hot. When the oils break down you were left with an oil that had poor lubrication properties. Honda didn't want to specify use of synthetic oil only which would have opened the door for other 30 weights. I believe 10w30 was the most stable conventional oil viscosity at the time the engine was being engineered. They did show some flexibility in spec'ing 5w40 as they knew those oils would likely be a high quality synthetic. They didnt stray from that first oil recommendation through the years as the vehicle was initially certified with 10w30 oil and they didn't see the need to re-certify it with other oils, certification costs money and they were obviously happy with the 10w30 and 5w40 recommendation.
I'm sure 10w30 still provided the necessary cold flow properties for critical engine parts or Honda wouldn't have spec'd it. Saying that today's synthetic 0w30 and 5w30 oils offer all of the hot temp protection coupled with superior cold flow improvements ,it's the best of both worlds if you drive your car in cold weather environments. If the S2000 was being developed today they likely would list 5w30 and 0w30 as permissable oils.
I'm sure 10w30 still provided the necessary cold flow properties for critical engine parts or Honda wouldn't have spec'd it. Saying that today's synthetic 0w30 and 5w30 oils offer all of the hot temp protection coupled with superior cold flow improvements ,it's the best of both worlds if you drive your car in cold weather environments. If the S2000 was being developed today they likely would list 5w30 and 0w30 as permissable oils.
06-12-2011, 08:57 PM
#9
Nice pics and info. After reading this post I decided to take my vtec solenoid apart and inspect it. Everything looked to be in good shape, fairly clean , I just gave the screen a thorough cleaning and put everything back together after a good inspection.