Thanks for the response.
I have a 2000 Civic Si with a VTEC, so I am familiar with the VTEC concept. You are correct that it does not work very well on a cold engine.
I have to believe that catalytic converters clean up oil smoke, but I could be wrong. I have seen dozens of posts on this forum and others where people say "where is my oil going? It is not leaking anywhere and there is no smoke..." At one point, my Lumina used a quart of oil in 650 miles and there was no visible smoke from the exhaust. For this reason, I think the catalyst removes it. From what I have read, additives in oil such as phosphorus will poison the catalyst. Now if you are not burning any oil, then the amount of phosphorus reaching the converter is negligable. If you are usnig a lot of oil, it will reduce the effectiveness and life of the catalyst. Make sense?
It would be only worse to use a thicker oil if you accept the premise that thicker oil causes some kind of problem. If you just review postings on here, you will see many many people use thicker oil with no consequences. If you look at Honda forums, you will see a lot of people use Mobil 1 15W50! The same Honda engines sold in Japan call out XXW40 oils.
My point in bringing up the 1997 Lumina is that I had a consumption problem that was almost cured largely due to Rotella 5W40. While it is not a VTEC, it has pistons, rings, etc. and the same consumption principles apply.
Great that there are no deposits on your plugs. Sometimes cars that burn oil end up with deposits on the plugs. It is not unusual.
Using a XW40 in a VTEC is absolutely no problem. You can think what you like. If I have a choice of using 30W and buring 1 qt / 1,000 miles, or using a 40W and burning half of that, I would take the 40W every time. I think most people would.
quote:
Originally posted by S2000driver:
Not making sense? Well, here is some thoughts for you:
The VTEC system on my car is made to not function until the car is warmed up.
Catalytic converters do not "take care of" oil smoke.
Catalytic converters will burn off oil from the catalyst due to a high operating temperature. Therefore, even a quart of oil every 1000 miles will have no effect on it (running rich can melt it down, however!)
If oil thickens a grade during use, wouldn't it be even worse to use a higher grade than specified?
From what I understand, the 1997 Lumina has NONE of the features listed in my previous post.
I've seen my spark plugs and crown of my pistons. No problem with oil deposits whatsoever.
quote:
Originally posted by CJH:
Your reasoning doesn't make sense to me.
If your car is consuming a significant amount of oil, deposits tend to accumulate in your combustion chamber and on your spark plugs. Except for the most extreme cases, the catalytic converter takes care of the smoke, but what effect do you think this has on the catalytic converter? Of course it shortens its life and effectiveness. Using a grade thicker oil resolves these problems, at least to a degree.
If thicker oil caused problems with your Vtec system of engine, then you would have problems as soon as you started it, because the cold oil is WAY more viscous than warm 30W oil is when it is hot.
If you look at the UOAs on here, you will see it is very common for oils to thin or thicken one grade during normal use.
BTW, I have been running XW40 oils in my 1997 Lumina (GM recommends XW30) for the past 20,000 miles and have not seen any kind of an adverse effect, nor would I expect any.
