the biggest problem with all 4AG's is the crank oiling. nearly every one that comes to our engine shop for repairs, has an identical problem. this can be helped by changing to the latest spec, 3/4 grooved main bearings, as it gives slightly better crank pin oiling.
I have never seen a stock 20V piston fail in a street car, and only once in a race engine.
IMHO the thin TRD head gaskets are just a wank. after you remachine the head and block faces to get them to seal properly, the compresison ratio is raised ever so slightly, and with our notoriously variable, fuels, you can get more detonation problems
PM if you want more detailed info or see .
