Motor oil debate - interesting info but a long read.

[Don Mason]

"Use only the Moly Paste, Part Number 99002-1. It has the necessary zinc to help in Lobe wear ." That is what is included with the their cams. "This Moly Paste must be applied to every cam lobe surface, and to the bottom of every lifter face of all flat tappet cams."
Roller tappet cams only require engine oil to be applied to the lifters and cam." Also, apply the Moly Paste to the distributor gears on the cam and distributor for all camshafts."



Much of this information is concerning premature wear in flat tappet engine designs utilizing push rods and rocker arms for valve actuation, primarily cam lobes and the followers (lifters).

Most modern engines are not of this type. In most, an overhead camshaft design is used. The design has far less valve train inertia and mass, so valve springs need far less tension to prevent valve float at high RPM's. The other added benefit is less power required to run the valve train, yielding more miles per gallon.

I wouldn't worry too much about the valve train in the Yaris, when using modern lubricants.