Motor oil weight for triton v10

427435 wrote:
A 5w-20 oil is no thinner at, say 0 degrees, than a 5w-40 oil. They both meet the viscosity requirements for a 5w oil at cold temps. And a 5w-40 oil is far thinner at operating temp than either 5w-20 or 5w-40 is at start up temps.

The person that said the 5w-20 oils are for improved mpg is spot on.

True about the 5w's being about the same cold, cold pouring no different. Not so with 10w30 etc.

But one must rethink about the so called 20 wt mpg factor. Since the 5w20 oil is thinner than the 5w40 at high temps, it flows(leaks away) faster. The pre-set pump torsional load force remains about the same (30-40# oil bypass) and more hot 20 weight is ultimately pumped through bearings in volume, than hot 40 weight. Basically the comparable hp parasitic drag of pumping either oil ends up about the same when hot, so the "claimed marketing" mpg gain of 20 becomes basically moot.

The Ford Triton engines pressurize the RH cam tensioner only after the oil has traveled from the front pump all the way to the rear of the engine, up to the RH head and forward all the way to the RH tensioner piston. The revised 20 weight oil better maintains more even pressure over this long passage than heavier oil. Oil pressure over lengthy passageways drops just like long, small garden hoses drop sprinkler pressure furthest from the supply. Ford has had some minor issues with the RH cam and RH tensioner over this long oiling path and 5w20 helps solve it. (The V-10 is longest of all.) Of course they are not going to advertise this.

I haven't seen it done, but I imagine installing a custom direct oil line, pump-to-the-front of the RH cam, would be a good performance durability mod. The LH head already oils this way. With no distributor shaft cam drive, the Triton oil pump is totally forward, keyed on the crank snout right in front of the 1st main bulkhead, not set back (centered-like) nearer the 2nd main web like older Ford engine designs, or 3rd web like early GM.

Wes
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