Originally Posted By: OVERK1LL
Originally Posted By: Gokhan
Chances are that the valve-stem oil seals have just given out. The only thing that will reduce the oil consumption is to switch to a higher kinematic viscosity, such as xW-40. NOACK volatility etc. won't make much difference.
My 4A-LC virtually completely stopped consuming oil, save for a minor leak at the oil pan, after I replaced the valve-stem oil seals. I run 0W-20 now. Before I replaced the valve-stem oil seals, I had to run 15w40 in order to control the oil consumption. From 0W-20 to 15w40, there is about a factor of 4 in oil consumption, which seems to be inversely proportional to the square of the kinematic viscosity:
Oil consumption ~ 1/(kinematic viscosity)^2
(empirical formula from my own experience)
I highly doubt it. It doesn't smoke, EVER. It used 1.5 quarts of oil in 8,000 miles. This is hardly excessive consumption, simply more than what it has used in the past.
With bad valve-stem oil seals, you would only see smoke when you drive off from a red light after having idled for more than a minute with a hot engine. You don't see smoke when idling or during cruising with bad valve-stem oil selas.
It's possible that some of the valve-stem oil seals have given out and the others will give out in the next few years. If you have four bad seals now, when all 32 give out, the oil consumption will get 8 times as bad; so, you would have to add 12 quarts of makeup oil in 8,000 miles. Valve-stem oil seals are made of synthetic rubber and they eventually give out, usually after 15 - 20 years. Therefore, it's quite likely that your oil consumption will gradually get worse as your valve-stem oil seals age more. You may eventually need to have them replaced or use xW-40 to control the consumption, but right now the 0.2 quarts per 1,000 mile consumption with xW-30 is still fairly small. If you used xW-20, the consumption would be about the double.