Pennzoil Platinum Pure Plus Motor Oil
07-14-2014, 08:51 PM
#46
Pro
I respect Doug's research and testing, and even followed in his footsteps with my 81. On a July day my oil pressure fell to zero at idle, the warning light came on and my lifters sounded like they were going to leave the engine. As soon as I got home, I switched to 15w-50 and haven't had a problem since.
I was not the only 928 owner who experimented with this based on Doug's findings who had similar results. Andrew Olson also had a bad experience testing 5w-40 Rotella in his GT.
I don't need to be an oil expert to know my 928 does not like 5w-40 Delvac.
I was not the only 928 owner who experimented with this based on Doug's findings who had similar results. Andrew Olson also had a bad experience testing 5w-40 Rotella in his GT.
I don't need to be an oil expert to know my 928 does not like 5w-40 Delvac.
Rotella 5w-40 is not Delvac 5W-40 despite the 5W-40 on the bottles.
(Rotella Group III oil vs Delvac Group IV = higher film strength and better shear properties).
A most important number is the 150C HTHS. Porsche lube spec requires > 2.5. Delvac HTHS is 3.3
Rotella don't publish the 5W-40 HTHS value.
Re your Delvac experience: is your oil pump in good condition? Just a possibility.
JC.
07-14-2014, 09:57 PM
#47
Administrator - "Tyson"
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Yes, I pulled it a few months after this (routine maintenance, figured I should do the seal) no pump issues.
If I was the only 928 owner who had similar experience with 5w-40 Delvac you could be onto something. I highly doubt the others that also tested this oil in the 928 only to experience pressure issues all have faulty oil pumps.
Not to mention, if you have ever taken a 928 oil pump apart you would know how robust they are. There isn't a whole lot to go wrong unless you experience an outright complete failure, a situation like this would not be "fixed" by a thicker oil as you implied happened with my engine.
As you stated, not all 5w-40's are created equal, which is why I pointed out Andrew Olson as another data-point for a different 5w-40.
IMO this reinforces why no 928 in a summer climate should see anything less than 15w-50, even in Wisconsin.
On top of all this, every 928/944 engine builder I've seen post with any authority on this subject (like Greg Brown) have been preaching for decades these engines were not made for the thinner oil. I doubt they are shilling for any oil company trying to clear the shelves of thicker oil.
As for 5w-40 Delvac, I use it in winter in two of our cars driven over the cold months that call for 5w-40. If my 928 were driven in the cold climate, I would be using 5w-40 Delvac over the freezing months in it as well.
In July on a 100 degree day? Not a chance, not doing that again.
Just to reinforce what JET951 said, I'll trust any experienced wrench and / or engine builder over any oil analysis. Especially when their advice mirrors the owners manual.
Can I explain Doug's experience? No, and I'm not even going to try. It's awesome that it works for him.
If I was the only 928 owner who had similar experience with 5w-40 Delvac you could be onto something. I highly doubt the others that also tested this oil in the 928 only to experience pressure issues all have faulty oil pumps.
Not to mention, if you have ever taken a 928 oil pump apart you would know how robust they are. There isn't a whole lot to go wrong unless you experience an outright complete failure, a situation like this would not be "fixed" by a thicker oil as you implied happened with my engine.
As you stated, not all 5w-40's are created equal, which is why I pointed out Andrew Olson as another data-point for a different 5w-40.
IMO this reinforces why no 928 in a summer climate should see anything less than 15w-50, even in Wisconsin.
On top of all this, every 928/944 engine builder I've seen post with any authority on this subject (like Greg Brown) have been preaching for decades these engines were not made for the thinner oil. I doubt they are shilling for any oil company trying to clear the shelves of thicker oil.
As for 5w-40 Delvac, I use it in winter in two of our cars driven over the cold months that call for 5w-40. If my 928 were driven in the cold climate, I would be using 5w-40 Delvac over the freezing months in it as well.
In July on a 100 degree day? Not a chance, not doing that again.
Just to reinforce what JET951 said, I'll trust any experienced wrench and / or engine builder over any oil analysis. Especially when their advice mirrors the owners manual.
Can I explain Doug's experience? No, and I'm not even going to try. It's awesome that it works for him.
07-14-2014, 10:35 PM
#48
Pro
Yes, I pulled it a few months after this (routine maintenance, figured I should do the seal) no pump issues.
As you stated, not all 5w-40's are created equal, which is why I pointed out Andrew Olson as another data-point for a different 5w-40.
IMO this reinforces why no 928 in a summer climate should see anything less than 15w-50, even in Wisconsin.
In July on a 100 degree day? Not a chance, not doing that again.
Can I explain Doug's experience? No, and I'm not even going to try. It's awesome that it works for him.
As you stated, not all 5w-40's are created equal, which is why I pointed out Andrew Olson as another data-point for a different 5w-40.
IMO this reinforces why no 928 in a summer climate should see anything less than 15w-50, even in Wisconsin.
In July on a 100 degree day? Not a chance, not doing that again.
Can I explain Doug's experience? No, and I'm not even going to try. It's awesome that it works for him.
Re your comment about oil analysis: you probably don't trust your blood test results either so what type of Dr do you go to?
JC
