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I am just wondering if anyone out there has some experience with higher viscosity oils. My oil pressures are dropping dangerously low at idle. I installed a 7psi safety switch on my motor just in case my oil pump belt were to ever fail. I was out with a buddy today doing some tuning and my safety switch activated twice at idle. Once the revs come up the oil pressure jumps up as well. The car has dome oilers, 180 degree main oiling and the two turbos. I figure there is just too much there to maintain oil pressure once the oil is hot. The engine is dry sump with the largest pressure section I can find. When cold oil pressure maintains a solid 75 psi. I am currently running 10w-40 conventional for break in. A buddy who runs a local speed shop says they have been having great results with the new 10w-60 wide range synthetics and recommended that I try them. I hate to use something so thick for fear of inadequate flow but many of the high performance oil companies advertise these for high performance turbocharged/supercharged applications. Any ideas??

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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
Last edited by George P
First, I'm not telling you to do anything. I just want to add an observation here.
I had a friend that was running NHRA ProStock. BB GM.
It was dry sump, pre-heated oil, etc.

At the green light the pressure would be 100psi. Coming back into the pits it would be like yours, under 10.

That was stright weight racing oil.

The feeling was that was normal and the 1000horses just ate it up.

Sounds like you have a similar scenario.
Back in my racing days I found that 20w-50 full synthetic did the trick.

The Mobil 1 high milage synthetic must have some kind of a viscosity stabilizer added to keep it from breaking down.

That might help this problem also.

My Pantera hasn't been a problem with oil pressure and I'm not stock.

My Shelby has with it's 347/302.

I had to mix 5w-30 and 20w-50, Mobil 1 Extended milage, 50/50, to get it to keep 30psi hot.
Conventional oil would drop to 10-15psi hot after only a couple of"laps". Just like the race car would.
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