Oil pressure VS Diffrent Brand

[crazycrak]

A friend of mine has a 2008 Dodge Ram 3.7L V6 and he has been running PP since the first oil change on the truck he says it usally holds around 80 psi at redline He just changed the oil to Valvoline SynPower and he said hes noticed the oil pressure now hold at 90 psi at redline both oils used are 5w-20 the truck has about 30K miles
why is it that its running more oil pressure with a diffrent oil?

 

[Turk]

Ask what was the oil pressure when the PP was "new" also.

 

[mcrn]

Did he put the same amount in? Maybe the valvoline is thicker?

 

[crazycrak]

yeah 5 qrts each time

 

[J. A. Rizzo]

The oil pressure drops as the oil heats up. Were both checks done while the oil was definitely at full temperature? Thicker oil will result in higher pressure. The Valvoline is probably thicker than the PP. This is nothing to be concerned about.

 

[crazycrak]

yes the engine was at op.temp. with both

 

[Fazzone]

I had a similar expeience myself when I switched between Cenex to Mobil oil. Thought it was odd, but the Mobil always ran about 5-7 psi less. Keep in mind that wasn't synthetic though. I'd think it would be a lot less likely with a synthetic.

 

[Chris71]

Some oils can be on the thinner or thicker side of a given weight. For example, Pennzoil Yellow Bottle 10w-30 is thinner than Pennzoil High Mileage 10w-30 at full temperature. The result is the HM will show a little higher oil pressure even though they are both the same weight.

 

[sl1driver]

Originally Posted By: Chris71
Some oils can be on the thinner or thicker side of a given weight. For example, Pennzoil Yellow Bottle 10w-30 is thinner than Pennzoil High Mileage 10w-30 at full temperature. The result is the HM will show a little higher oil pressure even though they are both the same weight.


Yes, the PP is a bit on the thin side for a 30 weight. A VOA posted on BITOG shows that the viscosity of the PP is 10.11 cST at operating temperature. The PDS for the SynPower shows it to be 10.5 cST. I don't know if that is enough of a difference to account for the higher pressure.

 

[sl1driver]

Originally Posted By: sl1driver
Originally Posted By: Chris71
Some oils can be on the thinner or thicker side of a given weight. For example, Pennzoil Yellow Bottle 10w-30 is thinner than Pennzoil High Mileage 10w-30 at full temperature. The result is the HM will show a little higher oil pressure even though they are both the same weight.


Yes, the PP is a bit on the thin side for a 30 weight. A VOA posted on BITOG shows that the viscosity of the PP is 10.11 cST at operating temperature. The PDS for the SynPower shows it to be 10.5 cST. I don't know if that is enough of a difference to account for the higher pressure.


OK, I'm a little slow today. I just noticed that you are referring to 5W-20, not 5W-30. However, I assume the same would hold true. The PP is probably on the thin side in each viscosity grade. But again, I'm not sure that would completely account for the difference in pressure.

 

[maximus]

How was the oil pressure determined? I don't give much credit to the gauge built into the cluster. Usually, they're just 3 way switches.

Hook a real mechanical gauge up to the port and take some averages with each brand.

As long as oil is getting to the bearings and valvetrain under sufficient pressure, all is fine. Anything above 60 is fine. Too much pressure is a problem.

 

[H2GURU]

I think that pressure is taken as an indicator by the novice but the VOLUME is of more importance to the engine's internals. Over the past several years on-highway trucks have seen a switch to a larger volume type pump.