I recall Castrol GTX (do they still make it?) having a great film which doesn't dissipate like most other oils. This stuff stopped the oil consumption of a Ford 460 cu in truck engne that the owner was about ready to torch.
Aye, Phillip touched on a point in the "camry Oil change mess" thread
> that I would like to chase down.
>
> Is it advised to go to thicker oil as a car ages.
>
> I have an '87 Corolla. It uses about a quart of oil every three months.
> Several little "seeps" here and there that my mechanic says are not
> worth spending money on.
>
> I have religiously changed the oil and filter every 3,000 miles
> following the break-in period with the recommended 10W-40 oil. Good oil
> and good filters.
>
> Now, with 230K on the car and a "noisy" engine, would I be advised to
> shift to another oil. I'm in the Pacific Northwest where we will have
> an occassional 28-degree low, but for the most part the winter driving
> temps are mid 30s to mid 50s and in the summer it ranges from lows of
> 55 to the rare 102.
>
> Mostly local, low speed, country driving.
>