I tried this once before with 10-40, but it wasn't synthetic high milage. Maybe I should try one more time with synthetic high mileage 10-40 before taking the plunge and replacing the valve seals.

I believe the high mileage oils have additives to condition and swell the valve seals. Did you see any difference with the 10-40 you tried previously? Was it synthetic?

Fixed it for you.

If oils marketed as "high mileage oils" had additives that could specifically target valve stem seals, and swell up hardened valve stem seals to restore their functioning, I wonder how those additives would know which seals were valve stem seals, and which other seals in the same engine would be worsened by swelling. What if the other seals were the right size, and swelling made them fail?

More claims by snake oil vendors.

That's the down side to using the oil additives for blue smoke/leaky valve seals, its going to saturate all gaskets. As for the high mileage oils, I believe thy have a smaller quanity of this additive.

It seems to me, one of the problems that is occurring with the 4.8is is that the oil is puddling up in the valleys where the valve stem seals are. This is caused in part by the oil not draining quickly enough back into the oil pan. If that is the case, then a thinner oil may in fact help alleviate some of the problem. Even a slightly used valve stem seal would probably leak if it were continuously submerged in oil. Any thoughts?

0w20 didn't help
 

I went to autozone today and picked up 9 bottles of mobil 1 synthetic 0w20, and I changed my oil this evening. I took my car for a test drive to see if it helped and I'm afraid to say that it didn't, and may smoke even more. I'm going to give it a few more days of driving and see if it's better or worse. But at this point it appears that my theory that a thinner oil may help was wrong.

I told you guys above 10w-40 fixed my problem for the most part, still smokes a LITTLE occasionaly but nothing compared to huge clouds before after 30 sec hot idle.

Also to all the sherlocks who say it isnt an approved oil and this and that... PLEASE.. Its so annoying, as long as its a good brand of full synthetic its all decent, its not like anyone is recommending vegtable oil.. Its not like changing the weight of your oil is going to kill your engine in 5 miles.

10w-40 is not good for year round though if you live where theres winters, i would switch to 5-40 for winter, other then that it will be fine.

And last post i believe is craig, yeah if you read above i posted the fix, in that thread i explained everything and 5-20 did not work, could have saved some time if you read it (not to come off as an ass, but i did post it)

Do 10-40 it will help.

I did read your post before, but I had already tried your method and it did not help me, so I was trying something else. I'm coming slowly to the sad realization that I'm going to have to change the valve stem seals.

Ok 10-40 Mobil 1 high milage this weekend it is. Ill tell you how it goes.

Also i may have noticed that in the shop we used to have 5-40 and ever since we changed back to 5-30 i started smoking... didnt make that connection at first but i hope its true. If it is, it means ive always had this problem since i bought the car..

Keep us posted late next week with your findings :)