Reply to "Oil Viscosities"

10W40 and 10W60 are basically the same oil, i.e. a base oil with low viscosity of 10. The 10W60 variety has more viscosity stabilizer in it than the 10W40, making it thicker at the elevated temperature where the second measurement is made. 10W60 is not thicker than 10W40 when they are cold, they are identicle.

Ensure you are usng oil filters with high burst pressures, like the Fram HP1. The can employed in the HP1 is much thicker than a standard oil filter, and has a burst pressure of 500 psi.

I am at a disadvantage because I do not have information about "new" wide range synthetics. Normally wide range oil has been avoided by race teams because in the past that indicated the oil consisted of more stabilizer and less lubricant.

However, Amsoil has manufactured a syntheic oil for decades that has a multi-viscosity rating of 20W50, even though it has NO stabilizers in it, it is naturally thicker at elevated temperatures without stabilizers. If this is how the new wide range synthetics are formulated (thicker at elevated temp without stabilizer) then I say "rock and roll"! If not, then give Amsoil 20W50 some thought.

For the future you may want to consider installing a heater in your oil tank, and heating the oil before you start the motor, which is what race teams have done forever. This would allow you to use straight 50 or 60 weight racing oil if you chose to do so. The oil would be hot when you started the car and you wouldn't have those high pressures like you do now. This would not be praticle for a car that is used for road trips. You would not be able to control whether there would a place to plug the heater in every place you parked the car.

another option, raise the idle rpm of the motor to the point where the pressure jumps up above 7 psi when the motor is hot. If pressure is so high the relief valve is opening to regulate pressure when the motor is cold, a little extra rpm shouldn't hurt, pressure shall still be regulated by the relief valve.

cowboy from hell